Have you installed the Visual Studio Tools for Office runtime on the
client machine?

Outlook will not see the dll created by VS as a valid com add-in when
trying to add it manually.

On Oct 26, 4:17 am, pjerling
wrote:
Hi there,

Created a 2003 Office Outlook Add-in using Visual Studio .NET 2005. When
installing the add-in on a non-development machine it appears that the add-in
is not appearing in the Com-Add-ins. I then tried to manually add the
add-in. But when I try to do that I receive the following error message...

path.dll is not a valid Office add-in.

Where do I go from now?