title: C# wrapper interface error: E_NOINTERFACE
body: <p>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 do this registration-free with the COM DLL--I'm using a manifest file to let Visual Studio know about SC_COM.dll, and that appears to be working.  I used TblImp.exe to generate a type library (SC_COMtlb.dll) that I'm referencing in Visual Studio 2008 so I can do early binding with the DLL that I need.  The DLLs are both in the same directory as the manifest and the executable.</p>
  
  <p>Here's the issue: When I instantiate the object and try and call one of its methods in C#, it throws the following error:</p>
  
  <blockquote>
    <p>Error detected: Unable to cast COM object of type 'SC_COMtlb.SCAccessObjClass' to interface type 'SC_COMtlb.ISCUploader'. This operation failed because the QueryInterface call on the COM component for the interface with IID '{C677308A-AC0F-427D-889A-47E5DC990138}' failed due to the following error: No such interface supported (Exception from HRESULT: 0x80004002 (E_NOINTERFACE)).</p>
  </blockquote>
  
  <p>I'm not entirely certain what this error means--I've done a search on the error code, and it appears to be a relatively general C# error.  So am I going about linking the COM object the wrong way here, or is there some other important step I may be missing?</p>
  
  <p>I should probably note that I'm not entirely sure how the type library (S\C_COMtlb.dll) that I produced knows where the actual COM DLL is, since it's not registered with the system--I assume it just looks in the same directory.  Could this potentially be the issue, and if so, how can I better link the two?</p>