error with Java3D under SGI

Hi,

When I tried to run the examples with visad package under SGI, those
without using Java3D worked well. However, Java3D gave me errors
like 
 
    Exception in thread "main" java.lang.NoClassDefFoundError: 
    javax/media/j3d/GeometryArray

I feel very confused because I can run all the examples on Solaries. 
I use JDK-1.2 on both platforms.

Does anybody know why? Thanks in advance. 


Yuan