Extremely difficult to debug, about EJB, JSP

Question

These codes are in a JSP page, an EJB will be looked up:
addcd.jsp
<%!
   private CDAdder cdadder = null;
   public void jspInit() {
      try {
         InitialContext ic = new InitialContext();
         Object objRef = ic.lookup("CDAdderBean");
        CDAdderHome home = (CDAdderHome)PortableRemoteObject.narrow(objRef, CDAdderHome.class);
         cdadder = home.create();
      } catch (RemoteException ex) {
            System.out.println("Remote Exception:"+ ex.getMessage());
      } catch (CreateException ex) {
            System.out.println("Create Exception:"+ ex.getMessage());
      } catch (NamingException ex) {
            System.out.println("Unable to lookup home: " + ex.getMessage());
   public void jspDestroy() {   
         cdadder = null;
%>
<%
HttpSession httpsession=request.getSession();
httpsession.setAttribute("cdadder",cdadder); //i want to add this object to the session so that i could retrieve it and use its methods in other JSP pages.
%>
<form method="post" action="addtrack.jsp">
<input type=text name="TitleOfTrack">
<input type=text name="DurationOfTrack">
<input type="submit">
</form>
......................................addtrack.jsp
<%
CDAdder cdadder=(CDAdder)request.getSession().getAttribute("cdadder");// get back the object in the session
String TitleOfTrack=request.getParameter("TitleOfTrack");
String DurationOfTrack=request.getParameter("TitleOfTrack");
cdadder.addTrack(new Track(TitleOfTrack,DurationOfTrack) ); //add the Track object into the arraylist using the addTrack(Track track) method in the CDAdderBean
response.sendRedirect(addcd.jsp); //redirect back to the addcd.jsp page
%>CDAdderBean.java
public class CDAdderBean implements SessionBean {
     // data item to hold a reference to a passed Session context     private SessionContext ctx;
     private ArrayList tracks=new ArrayList();   << This arraylist holds the Track objects
     public void addTrack(Track track) throws RemoteException{
          tracks.add(track); //one method for adding tracks to the arraylist
     public void removeTrack(int index) throws RemoteException{
          tracks.remove(index); //another method for removing a track from the arraylist
     public ArrayList getListOfTracksAL() throws RemoteException{
return tracks;
...............................Each time the user enters the required fields(title,duration) to add a track, these parameters will be passed to the addtrack.jsp, and the addtrack.jsp will retrieve the cdadder object from the session and use its addTrack method to add the track to the arraylist. And when it finishes, it will redirect back to the addcd.jsp. I got some other codes in the addcd.jsp(I did not show it as it will look very messy), anyway, the codes includes a call to the getListOfTracksAL() method which will return an arraylist of Track objects.
my problem is that, EVERY TIME i started the sun application server, and go to the addcd.jsp, then the FIRST TIME I entered all the required fields and click submit button . I expected the parameters would be passed to the addtrack.jsp and it would add the track to the arraylist for me and then returned to addcd.jsp and the addcd.jsp would display the track that I just tried to add.
but it didn't.
I am sure that it DID add the track to the arraylist because i tried to print the size of the arraylist after the addTrack method was invoked.
the most strange thing was that the addcd.jsp would display the tracks correctly after the FIRST TIME of adding a track.
Please take a look at this link if you have time:
http://222.166.192.130:8080/E-Music/login.jsp
username:aaaaaa
password:aaaaaa
choose the role as "Admin"
Add new music recording
note: processor.jsp in this web server is the addtrack.jsp I was referring to.
Many thanks to you all.

Answer 1

ya
i tried to add some println statements and noticed that:
the first time i tried to add a track, the addTrack method was really invoked and the size of the arraylist became 1
but when it returns to the addcd.jsp page the arraylist became empty
but the most strange thing was that, it worked correctly AFTER the first time.
thank you very much for your advice.