C# wrapper interface error: E_NOINTERFACE

Question

I am trying to produce a C# wrapper for a COM object that I have (named SC_COM.dll), but am having some issues linking it with Visual Studio 2008 (running Vista). I need to

Answer 1

the error code means that Visual Studio thinks that a certain object is supposed to implement a certain interface, but when I tries to "connect" to that interface the object responds that it doesn't know about it.

I would guess that the problem is in SC_COM.dll. TLBIMP.EXE extracts class and interface information from metadata stored within the DLL and builds wrappers for the class.

For example, if SC_COM is written in C++, this could happen if the creator of the DLL indicated in the IDL file that a class implements that interface, but the actual code doesn't support that interface.

Here's another common source of problems this DLL might have: sometimes you have a class implementing an ISomething2 interface which derives from an ISomething interface, but the class implementation to only recognize ISomething2. If you implement a derived interface, you must recognize its base interface as well. This is a common mistake.

Do you have (and control) the source code for the DLL?