A com addin works in F# but not in C#

Hello,

Has anyone ever come across a problem where a COM addin would be usable in F# code but not in C#?

I have a COM addin that I load into F# using System.Activator.CreateInstance(Type.GetTypeFromProgID(AddinName)),

where AddinName is the string containing the name of the COM addin. In F#, this call returns an object which is of type System._ComObject, but the same is not working in C# where I get a run-time System.IO.FileNotFoundException.

I have verified that the two projects reference the same dll and have the same build and debug settings.

Thanks,

Elena