Dave, I tried the iserror function on the variable in which I stuck
the VLookup return value. IsError never becomes true when VLookup
fails to find something. I resorted to using the Err object as
described at http://www.cpearson.com/excel/Callin...ionsInVBA.aspx.

It turns out that if there is an error, the left-hand-side does not
actually get a result.

I suuppose I could always try putting the VLookup expression inside
IsError as an argument, but then I'd have to repeat that expression to
assign to the destination variable when IsError evaluates to False.

Anyway, I'm sure this is motherhood to most, but it feels like I'm
finally starting to "operate" in the VBA environment.

Thanks again for the leads.