Excel Add-In could not load (xx.dll) during VB.NET Debug in VS2010

VS2010, VB.NET. Creating Excel Add-In with Ribbon. When I start debugging (F5), Excel launches find but my Add-In does not load. I am getting this error message after Excel 2010 opens:

Could not load file or assembly 'SatelliteRibbon, Version=1.0.0.0, Culture=neutral' or one of its dependencies. The given assembly name or codebase was invalid. (Exception from HRESULT: 0x80131047)

It seems to work fine on another developer's machine.

I have break points set on Add-In Start Up and Ribbon Load. They never execute. I have the source code and files in a trusted location. All Macros, etc I have set to "allow" or enabled.

Any ideas?