ActiveX Problem

I wrote an activeX control in VC++. When I use the control in VC++ application, it work perfectly. However, when I use it in VB, it failed. Finally, I found out that the control never call the Create method, and thus the member variable m_hWnd (which is the window handle of that control) contains NULL !! how can this happen, does any one has this experience ??

Any advise is appreciated. Thanks