Display.RGB prob on Java3D Linux-7.0

hi,
        Thanx bill and Jack for ur active replies.
        Well I still hav one more at my disposal
        Can any one help me out.
        I am not getting the Display.RGB mapped on 
        the visad application.As a result the data is not 
        being displayed .
        how can I get the data in RGB
yours
Praveen