Ubuntu Java JLayeredPane error

I have an issue with a program i am working on, It is a Java program but it runs differently in windows. Thats the whole point of Jva is to not have to write it multiple times. I though it could just be linux in general being different than windows but i get the same problem in Mandriva. Here is the problem. I have a JLayeredPane that i have an image on and i have put buttons under the image. in Ubuntu, while i am running the program, the buttons stay behind the picture ( thats what i want it to do ), but in Windows and Mandriva, when i scroll over the button they move on top of the picture. I know that there are other ways just to program it, but i just wanted to know if there was a problem with Ubuntu or Java and Ubuntu.

You'll get a sooner answer after you provide a way to test your program and also let people know what Java versions you're running on windows and Linux.