Unable to locate the application's 'main' class...

I've just got a error message from java application on Fedora 10 like:

Unable to locate the application's 'main' class. The class 'blahblahblah' must be public and have a 'public static void main(Stri
ng[])' method. (LAX)

with openjdk.
As a result, I have to install libXp.i386 package on my x86_64 box. it's not easy to imagine what's wrong... bah.