I have a 3rd party .dll that I have successfully added as a reference in both a VS 2010 C# project and an F# VS 2010 project. I can view the contents in the object browser in both cases, but the F# version won't let me "open" the library. It works fine in the C# project (with the "using" directive), and I can write a program that uses the contents of this particular .dll. I have not had any trouble with other .dlls in F#/VS 2010/.NET 4.0 on Windows 7.
Any ideas as to why this might be happening? Or how I could debug this further?