Urgent : everything works fine, but cannot find a .jpg file

Question

This is my first attemp at creating a jar file and running the running the program
i created a jar file ran it, everything works fine but when i click the about menuitem, it throws a java nullpointer exception,
it says it cannot find the .jpg file that is used for the about box,
the code works fine if i run as a normal program i.e
java <somepackage>/<classname>
javax.swing.ImageIcon aboutimage;//in the constructor
try{
aboutimage = new javax.swing.ImageIcon(getClass().getResource("resources/image/"+"About.jpg")); //-- exception at this line
               }catch(Exception e){
                    e.printStackTrace();               
               }

Answer 1

i post a bit more details in case sm1 might want to refer,
Thanks in advance ..it's a bit long sorry for the inconv.
I created a jar file this way,
- first created the Manifest.txt file and added the the main class,
follwed steps from the tutorial at sun:
http://java.sun.com/docs/books/tutorial/deployment/jar/appman.html
then this at command prompt
jar cfm Aid.jar Manifest.txt IDTT/
Now when i run the jar file every thing runs fine except for the About.jpg,
that file doesn't show up when i click the about button in the application
Everything works fine when i directly run the file from command prompt as java IDTT/Aid
Error recieved:
Exception in thread "AWT-EventQueue-0"
java.lang.NullPointerException
at javax.swing.ImageIcon.<init>(Unknown Source)
at IDTT.Aid$AboutPanel.<init>(Aid.java:336)
at IDTT.Aid.menuItem_AboutActionPerformed
(Aid.java:304)
this is line 336 in Aid.java:
javax.swing.ImageIcon aboutimage = new javax.swing.ImageIcon(getClass().getResource("resources/"+"About.jpg"));
Aid.java has package as
package IDTT,
the files in folder graph
have package as
package IDTT.graph
"resources" is a normal folder that has a image file called About.jpg
and another folder called "html" that contains many html files.
there's no error for html files
This is the package/folder tree structure
IDTT
|
|- Aid.java (has main)
|
|- graph (a package that Aid.java uses)
|
|_ resources
    |
    |- image
    |      |--- About.jpg
    |
    |- html