member variable wizard not available in MFC extension DLL

I have an application with MFC extension DLL's with dialog's both in the main app and in the DLL's. Apart from care in the resource Id specification it works fine using classwizard in Vc 6, allowing me to define member variables in the min app and the dll's.

However on converting to Vc.Net the Add Member Variable wizard is unavailable for the dialogs in the DLL's, but seems to work normally in the main app. Why is this so ? and is there a work-around ? Is this related to resource issues. All the code and variables generated by Vc 6 work fine,I just can't see or modify them except probably manually.