Overidden CWinApp::OpenDocumentFile does not get called

Hi,

I am using VS 2010.

I have an MFC executable (MDI app with multi-document tempates) and I have overridden the CWinApp::OpenDocumentFile member, becuase I needed some custom validation.  This works fine.  Now I have an MFC Extension DLL that is loaded dynamically in the app.  This extension DLL calls:

       AfxGetApp()->OpenDocumentFile(...)

But the thing is that the above call is not going through my overridden CWinApp::OpenDocumentFile.  But I need it to go through my overridden CWinApp::OpenDocumentFile.   What am I doing wrong and what should I do?

Thanks in advance.

Mizan Rahman