Use 16 bpp with GRASS

PS. I get the Error Message such below .....

Mapset <botany> in Location <TWR>
GRASS 4.1 > d.mon x1
X Error of failed request: BadMatch (invalid parameter attributes)
  Major opcode of failed request: 78 (X_CreateColormap)
  Serial number of failed request: 73
  Current serial number in output stream: 74
Please start graphics monitor <x1>.
Error - Graphics monitor <x1> not running!
Problem selecting x1. Will try once more
Please start graphics monitor <x1>.
Error - Graphics monitor <x1> not running!

Mapset <botany> in Location <TWR>
GRASS 4.1 >

Thank you again.
Grass User
Der-Johng Sun <r3206009@cc.ntu.edu.tw>