No-cache not expiring web page

Question

In the below servlet A i am able to get the no cache to work so when i hit the back button the page is expired.
I am using this same exact code in another servlet. The only differenc i can think of is the i am using the PRG patten with it. So i do a process then it redirects to servlet B and displays the invoice page. However if i hit back from here the page is not expired and will still display.
any ideas?
thanks john
SERVLET A
public class NewRegistration extends HttpServlet{
     public void doGet(HttpServletRequest request,
               HttpServletResponse response)
     throws IOException, ServletException
          HttpSession session = request.getSession();
          User user = (User) session.getAttribute("user");      
          Cart cart = (Cart) session.getAttribute("cart");
          session.setAttribute("cart", cart);
          session.setAttribute("user", user);
          //session.setAttribute("Checked", "CHECKED");
          session.setAttribute("isChecked", "isChecked");
          response.setHeader("Pragma", "No-cache");
          response.setHeader("Cache-Control", "no-cache");
          response.setDateHeader("Expires", 1);
          String url = "/register.jsp";
          RequestDispatcher dispatcher =
               getServletContext().getRequestDispatcher(url);
          dispatcher.forward(request, response);
     public void doPost(HttpServletRequest request,
               HttpServletResponse response)
     throws IOException, ServletException
          doGet(request, response);
}SERVLET B
public class DisplayInvoiceServlet extends HttpServlet
    public void doGet(HttpServletRequest request,
            HttpServletResponse response)
            throws IOException, ServletException
        HttpSession session = request.getSession();
         String Error = (String) session.getAttribute("Error");
         String processerror = (String) session.getAttribute("processerror");
                                response.setHeader("Pragma", "No-cache");
          response.setHeader("Cache-Control", "no-cache");
          response.setDateHeader("Expires", 1);
          String url = "";
          if(Error !=null){
               url = "/confirm.jsp";
               session.setAttribute("Error", Error);
          else if(processerror != null){
               session.setAttribute("processerror", processerror);
               url = "/carderror.jsp";
          else{
               url = "/invoice.jsp";     
        RequestDispatcher dispatcher =
                getServletContext().getRequestDispatcher(url);
        dispatcher.forward(request, response);
     public void doPost(HttpServletRequest request,
               HttpServletResponse response)
     throws IOException, ServletException
          doGet(request, response);
}

Answer 1

The redirect in this servlet goes to servlet B. This is the servlet described in the first post that i didnt include.
public class SubmitOrderServlet  extends HttpServlet
     public void doGet(HttpServletRequest request,
               HttpServletResponse response)
     throws IOException, ServletException
          String cardType = request.getParameter("Ecom_Payment_Card_Type");
          String cardName = request.getParameter("Ecom_Payment_Card_Name");
          String cardNum = request.getParameter("Ecom_Payment_Card_Number");
          String expMonth = request.getParameter("Ecom_Payment_Card_ExpDate_Month");
          String expYear = request.getParameter("Ecom_Payment_Card_ExpDate_Year");
          String cvvCheck = request.getParameter("group2");
          String cvv2 = request.getParameter("Ecom_Payment_Card_Verification");
          String bankPhone = request.getParameter("bankphone");
          HttpSession session = request.getSession();
          User user = (User) session.getAttribute("user");    
          Cart cart = (Cart) session.getAttribute("cart");
          Icharge icharge = new Icharge();
          Cardvalidator validate = new Cardvalidator();
          GenericValidator validator = new GenericValidator();
          DecimalFormat format = new DecimalFormat("0.00");
          String Error = "";
          boolean proceede = true;
          try {
               validate.reset();
               if(cardType.equalsIgnoreCase("0")){
                    Error = "Please Select Card Type";
                    proceede = false;
                    session.setAttribute("Error", Error);
               if(proceede){
                    if(!cardName.equalsIgnoreCase(user.getformatBName())){
                         Error = "Cardholder name must match billing Information";
                         proceede = false;
                         session.setAttribute("Error", Error);
               if(proceede){
                    if(expMonth.equalsIgnoreCase("Month")){
                         Error = "Please Select Exp. Month";
                         proceede = false;
                         session.setAttribute("Error", Error);
               if(proceede){
                    if(expYear.equalsIgnoreCase("Year")){
                         Error = "Please Select Exp. Year";
                         proceede = false;
                         session.setAttribute("Error", Error);
               if(proceede){
                    if(expMonth != null && expMonth.length() >0 && !expMonth.equalsIgnoreCase("Month")){
                         validate.setCardExpMonth(Integer.parseInt(expMonth));
               if(proceede){
                    if(expYear != null && expYear.length() >0 && !expYear.equalsIgnoreCase("Year")){
                         validate.setCardExpYear(Integer.parseInt(expYear));
               if(proceede){
                    if(cvvCheck.equalsIgnoreCase("cscY")){
                         if(cvv2 == null || cvv2.equals("")){
                              Error = "Please enter Card Security Code";
                              proceede = false;
                              session.setAttribute("Error", Error);
                         else if(cvv2 != null && (cvv2.length() < 3 || cvv2.length() > 4)){
                              Error = "Please enter a valid Card Security Code";
                              proceede = false;
                              session.setAttribute("Error", Error);
                         else if(!validator.isInt(cvv2)){
                              Error = "CSC must be numeric";
                              proceede = false;
                              session.setAttribute("Error", Error);
               if(proceede){
                    if(bankPhone == null || bankPhone.equals("")){
                         Error = "Please enter issuing bank phone number";
                         proceede = false;
                         session.setAttribute("Error", Error);
               if(proceede){
                    validate.setCardNumber(cardNum);
                    validate.validateCard();
               if(proceede){
                    if(validate.isDateCheckPassed() && validate.isDigitCheckPassed()){
                         try{
                              icharge.resetData();
                              icharge.setGateway(1);
                              icharge.setTransactionDesc("Ibiz Test Transaction");
                              String total = cart.getTotalPrice();
                              total = total.substring(1);
                              icharge.setTransactionAmount(total);
                              icharge.setCardCVV2Data(cvv2);
                              icharge.setCardNumber(cardNum);
                              icharge.setCardExpMonth(expMonth);
                              icharge.setCardExpYear(expYear);
                              icharge.setCustomerFirstName(user.getBillfirstName());
                              icharge.setCustomerLastName(user.getBilllastName());
                              icharge.setCustomerAddress(user.getBilladdress1());
                              icharge.setCustomerCity(user.getBillcity());
                              icharge.setCustomerState(user.getBillstate());
                              icharge.setCustomerZip(user.getBillzip());
                              //icharge.setInvoiceNumber("12345");
                              icharge.setTimeout(30);
                              icharge.authorize();
                              if(icharge.isTransactionApproved()){
                                   session.setAttribute("processerror", null);
                                   System.out.println("AVS " +icharge.getResponseAVS());
                                   System.out.println("resp " +icharge.getResponseCode());
                                   System.out.println("cvv " +icharge.getResponseCVV2());
                                   //System.out.println("respD " +icharge.getResponseData());
                                   System.out.println("resptext " +icharge.getResponseText());
                                   System.out.println("transId " +icharge.getResponseTransactionId());
                                   System.out.println("apprCode " +icharge.getResponseApprovalCode());
                                   java.util.Date today = new java.util.Date();
                                   CCData cardData = new CCData();
                                   cardData.setAvsResp(icharge.getResponseAVS());
                                   cardData.setCardholder(user.getBillfirstName() + " " + user.getBilllastName());
                                   cardData.setCardNum(cardNum);
                                   cardData.setCardType(validate.getCardTypeDescription());
                                   cardData.setCvvResp(icharge.getResponseCVV2());
                                   cardData.setRespApprCode(icharge.getResponseApprovalCode());
                                   cardData.setRespText(icharge.getResponseText());
                                   cardData.setRespTransId(icharge.getResponseTransactionId());
                                   Invoice invoice = new Invoice();
                                   invoice.setUser(user);
                                   invoice.setInvoiceDate(today);
                                   invoice.setLineItems(cart.getItems());
                                   if(cart.getTax() > 0){
                                        invoice.setIsTax("Y");
                                        invoice.setTax(cart.getTax());
                                   else{
                                        invoice.setIsTax("N");
                                   invoice.setSubtotal(cart.getSubtotal());
                                   invoice .setTotal(Double.parseDouble(total));
                                   Tender tender = new Tender();
                                   tender.setAmount(Double.parseDouble(total));
                                   tender.setTenderType(validate.getCardTypeDescription());
                                   InvoiceDB.insert(invoice,cardData,tender);
                                   StringUtils strUtil = new StringUtils();
                                   String items = "";
                                   for(int i = 0; i < cart.getItems().size(); i++){
                                        LineItem item = cart.getItems().get(i);
                                        Product p = item.getProduct();
                                        items = strUtil.addToRecWSAftr(items, String.valueOf(item.getQuantity() + strUtil.fillRight(String.valueOf(p.getItemNum()),17)) +
                                                  strUtil.fillRight(p.getDesc2(),29) + strUtil.fillRight(String.valueOf(p.getPriceFormat()),12));
                                   // Send an email to the user to confirm the order.
                                   String to = user.getEmail();
                                   String from = "[email protected]";
                                   String subject = "Order Confirmation";
                                   String body = "Dear " + user.getFormatSName() + ",\n\n" +
                                   "Thanks for ordering from us. " +
                                   "You should receive your order in 3-5 business days. " +
                                   "Please contact us if you have any questions.\n\n" +
                                   "Order Summary\n\n" +
                                   "Qty          Item No.          Description            Price\n"+
                                   "-----------------------------------------------------------\n"+
                                   items + "\n";
                                   boolean isBodyHTML = false;
                                   try
                                        MailUtil.sendMail(to, from, "", subject, body, isBodyHTML);
                                   catch(MessagingException e)
                                        this.log(
                                                  "Unable to send email. \n" +
                                                  "You may need to configure your system as " +
                                                  "described in chapter 15. \n" +
                                                  "Here is the email you tried to send: \n" +
                                                  "=====================================\n" +
                                                  "TO: " + to + "\n" +
                                                  "FROM: " + from + "\n" +
                                                  "SUBJECT: " + subject + "\n" +
                                                  "\n" +
                                                  body + "\n\n");
                                   session.setAttribute("invoice", invoice);
                              else{
                                   session.setAttribute("processerror", icharge.getResponseText());
                                   System.out.println("resptext " +icharge.getResponseText());
                                   System.out.println("resp " +icharge.getResponseCode());
                                   System.out.println("respD " +icharge.getResponseData());
                         catch(IBizPayException ex){
                              System.out.println("IPWorks exception thrown: " + ex.getCode() + " [" + ex.getMessage() + "].");
                         catch(Exception ex){
                              System.out.println(ex.getMessage());
                    else{
                         proceede = false;
          catch (IBizPayException ex) {
               Error = ex.getMessage();
               proceede = false;
               session.setAttribute("Error", Error);
          catch (Exception e1) {
               System.out.println(e1.getMessage());
          if(!proceede){
               session.setAttribute("cardI", cardType);
               session.setAttribute("expmI", expMonth);
               session.setAttribute("expyI", expYear);
               session.setAttribute("cardN", cardNum);
               session.setAttribute("cvv", cvv2);
               session.setAttribute("bphone", bankPhone);
          else{
               session.setAttribute("cardI", null);
               session.setAttribute("expmI", null);
               session.setAttribute("expyI", null);
               session.setAttribute("cardN", null);
               session.setAttribute("cvv", null);
               session.setAttribute("bphone", null);
               session.setAttribute("Error", null);
          response.setHeader("Pragma", "No-cache");
          response.setHeader("Cache-Control", "no-cache");
          response.setDateHeader("Expires", 1);
          response.sendRedirect("DisplayInvoice");
     public void doPost(HttpServletRequest request,
               HttpServletResponse response)
     throws ServletException, IOException
          doGet(request, response);
}