Calcomp digitizer problem

[PC_user]

Hi! GRASS programmers and users:

Could somebody help me with the digitizer Calcomp Drawing board III 
configuration? It seems that I couldn't let GRASS communicate with 
the digitizer. "Digitizer read error" is the message I always got after 
I hit <ESC> key at the v.digit's "MAP REGISTRATION POINTS" screen.  
I believe I have made everything correctly. It must be something
I miss through.
My system is running on PC 486 DX2 w/ 16MB memory.
The OS is USL SVR4.2 with Motif 1.2 /X11R5. 
The digitizer equips with a 4-buttons cursor, while I 
select cc95f23_16 for .dgt (could that be the problem?).

Thanks in advance!

Te-Hwa Hou