Yes, Michael, rights are OK. Thx to you and the others for suggestions.

I've been trying 3 different servers and discovered that on 2 of them
the standard ib_udf functions were indeed working properly but my
custom function/dll was not.

I just found out by accident that including the old gds32.dll (dated
7/14/2004) in the Windows/System32 folder seems to do the trick.
Doing the same with fbclient.dll does not work.

Hmmm, do I need to recompile my custom .dll?

It's not scientific, and it's not pretty, but that's what I've found
so far. Am about to try this on another server....

Thanks again-
-David