Can't allocate r/w color cells

I'm running MachTen UNIX on a Macintosh as an X server to GRASS on
a DEC alpha. When I try to open a graphics monitor, I get a message
that "Can't allocate read/write color cells."

The X driver works fine with lots of other X servers running lots of
other window managers.

Anyone have any clues what the problem could be?

Thanks in advance.

Neel Smith
smith@hcacad.holycross.edu