How to debug an Add-in for MS Project

Hello

I have made a COM Add-in in Visual Studio .NET 2003 by using a standard
shared Add-in project. Presumeable it should be possible to debug the
application by running MS Project under "start external program" at the
project property pages. When I start the debugger, MS Project is correctly
run, but the Add-in does not load. It does so if I register the Add-in using
the Setup Project I also created and then run MS Project manually. This is a
very hard way of debugging!
Can anyone help me to debug the Add-in in the intended way?

Thank you very much!

Troels Grosbøll-Poulsen