Talvez as limitações do net.exe listadas aqui?
NET.EXE /ADD command does not support names longer than 20 characters
The NET.EXE command does not support names longer than 20 characters for reasons of backward compatibility with LAN Manager 2.0.
For additional information about this LAN Manager 2.0 limitation, click the following article number to view the article in the Microsoft Knowledge Base:
131417 – Windows NT global groups are limited to 20 character names