[Help] xgrass on SGI

I use SGI 4D/35 to run Xgrass4.1, and found the following problems.

ON x-grass menu, I select 'Display' then 'Display Tool', it shown a dialog but
closed soon.
And the error message is:

Xgrass DISPLAY LIB ERROR: Not enough colors available. Make more available before strating again.

Why ?
How to resolve this problem? Please help!

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* Hong-Jei Hong Email:hjhong@ev004.ev.nctu.edu.tw *
* (IP:140.113.223.4) *
* Institute of Environmental Engineering Voice:011-886-35-712171x2929 *
* National Chiao Tung University *
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