Error running RMI program in Linux

Question

hi,
hope can get some advices and help from you all..my problems is like this:
There is no problem when i run my RMI client in Windows to send message to server. but when i run my RMI client in Linux to send message to server, exception occurs..here are the source codes...
****interface Task2*****
public interface Task2 extends Serializable {
    Object getSender();
    Object getReceiver();
    Object getText();
}****sdMssg.class********
public class sdMssg implements Task2{
        Sring sender, receiver, text;
     public sdMssg(String s, String r, String t) {
             sender = s;
          receiver = r;
          text = t;
     public Object getSender(){
          return sender;
     public Object getReceiver(){
          return receiver;
     public Object getText(){
          return text;
}when i click "send" in my message box,
public void actionPerformed(ActionEvent e){
     if(e.getActionCommand().equals("Send")){
     try{
     String input = lsd2.getText(0, lsd2.getLength());
     String mssg = new String(sender.getText()+": ");
     mssg = mssg.concat(input);
     try{
          sdMssg task = new sdMssg(sender.getText(), receiver.getText(), mssg);                    
          uL.sendMessage(task); //uL is the reference to the remote 
                                   //object.sendMessage is remote
                                   //method to send task object to
                                   //server
     }catch(Exception ex){
          ex.printStackTrace();
     lsd.insertString(lsd.getLength(), mssg + newline, attrs);
     lsd2.remove(0, lsd2.getLength());
     }catch(BadLocationException ex){}************************************************************************
the exception : java.lang.NullPointerException() at line uL.sendMessage(task)..do you know what is the problem? it's running very well in Windows but not in Linux..what should i do? i really need yours help..
Thanks a lot here..

Answer 1

sorry, it's my mistake..it really Naming.lookup problem..i have solved it..anyway, thanks for your kindness..