Java SE (Java Platform, Standard Edition)

hi
i've got a little problem: i created a java application in netbeans but when i start it, there is that error:

exception in thread java.lang.noclassdeffounderror: javax/media/opengl/gleventlistener

I know there are still threads in other forums dealing with that but i don't understand that s****.

I added "jogl.jar" and "gluegen-rt.jar " to my project, sothat the compiler 'should' find every class.
Could it be that a *.so-file ( a *.dll-file for linux) is missing?

thanks for you attention!