I've considered all the same possibilities. The R&D group is of course only one of the groups. As it happens, it's the only one with something other than pure alpha characters.

To eliminate the possibility of any kind error earlier in the script causing the problem I have run test scripts with nothing before the INGROUP test. Same results.

What bothers me most is the fact that this function apparently works for everyone else in the world. I could understand if other commands or functions failed but they don't.

For now at least I'll use the resource kit utility to work around the problem. If I ever do find the cause I'll make a point of posting it.

Thanks to everyone who took the time to think about it but unless someone else can duplicate the problem I think we'll leave it there.