On Thu, 12 Aug 2010 18:12:06 -0700 (PDT), Smartin
wrote:

Thanks for the suggestions, Dave. They are good ones for the books. I
now recall using the replace = with = trick to fix UDF calls in the
past. However, no luck with any of that today. I did make some headway
though. In the process of deleting and re-typing UDF calls I noticed
at one point the function I wrote as
=SmoothY(...)
turned into
=MyAddIn!SmoothY(...)
without my prompting.

Then I remembered -- I originally developed the function in the
workbook, then moved it later to the add-in. Near the same time I
moved the location of the add-in from a network to which I am not
always attached to the local C:. It seems the worksheet is confused
about where the function is located. I searched the installed projects
to ensure there is no duplication of the function name "SmoothY" -- it
only exists in the add-in. But I was able, at least temporarily, to
fix the worksheet by prepending "MyAddIn!" to the function call.

I will see how it goes over the next few update cycles (which includes
on and off the network).

Thanks again for your thoughts!

Somehow, between your add-in and your workbook, you have what I call
"name confusion". You are probably using the same UDF name in two
different locations. It could be the same function (name) in two
different modules; or maybe even a module that has the same name as
your UDF. Fix that and you should be OK.