I just turned UAC back on and it worked as usual during logon. UAC is enabled on servers, but set to a lower level by policy.

Did you try my code example? When I add
'  LPriv: ' $LPriv ?	
'   Priv: ' @PRIV ?
'IsAdmin: ' $IsAdmin ?
I get the following result:
  LPriv: Admin
   Priv: USER
IsAdmin: 5
IsAdmin is set to the position in the string where "Admin" was found, and would be 0 if not found. This works fine for true/false testing. (If $IsAdmin).

My workstation is Win-7 x64, FYI.

Actually I am a Rocket Scientist! \:D