weirdness when mapping to RGB

Hi all,

I'm working on a VisAD application, and found a problem when adding a
ScalarMap of (rng->RGB). I see not a coloured field, but a grey-brown
solid colour where there should be graded colour.

I was baffled, but found that on other machines, the code worked as
expected. One of the other programmers in my group suggested it might be
related to my video card or configuration in some way, and that there
was a discussion on something similar at one point here.

Can anyone give me some pointers on what causes this issue, and what the
resolution might be?

I can post screenshots if people think it would be helpful, but I don't
want to clutter your inboxes.

Thanks,
-Tennessee