When you said that it doesn't work for commands like this

IF INGROUP("Administrators")

is this a local oe global group?

typicaly the Administrators groups is a local group.

For local groups it is always best to place the computername before the group name.

example:

if ingroup("@wksta\administrators") = 2
? "You are in the local Administrators group on @wksta"
endif

Bryce