What DM Unseen means is that it appears that you created an Add-In. The
giveaway is the AddinInstance_OnConnection(). This sub is created for
add-in's.

What you want to do is start a new project as an ActiveX DLL. If you're
unfamiliar with how to do this, no offense, but you really should buy a
decent VB6 book. It's pretty easy but there's still too much to go into
on a forum. The upside is that you can often find good used VB6 books
for cheap these days.

Quickly, though, when you wrote
Private Declare Sub AddInMsg Lib "MySubAddIn.dll" ()

This is the wrong way to set a reference to a VB DLL. This syntax is
for Win32 API DLL's (simply put, DLL's that come with Windows). For
DLL's that you create, you will want to set a reference to them in your
VBA editor by using Tools References then browse for your DLL name.

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Nick Hebb
BreezeTree Software
http://www.breezetree.com