>>The developer of that C++ library is having the same problem as me. He can only debug in Visual Studio 2010 and in 2012 he is getting the same error. So, for now I don't have another choice than to mock that part.
>
>If you don't want to try to debug the actual C++ DLL, at least grab the function signature from the source code for it (ex. the line that says function xxx Invoke1 in the cpp file) and post it here.

This is main.cpp file of that project (I see lots of files in that project, so I don't know which one actually implements everything):

// main.cpp : Implementation of Cmain
#include "stdafx.h"
#include "Ww.h"
#include "main.h"
#include "mainengine.h"

/////////////////////////////////////////////////////////////////////////////
// Cmain


STDMETHODIMP Cmain::invoke(BSTR query, BSTR *result)
{
	AFX_MANAGE_STATE(AfxGetStaticModuleState())
	try
	{
		pMainEngine->InvokeCall(&query, result);
	}
	catch(...)
	{
		RecordExceptionInfo();
	}
	
	return S_OK;
}