How to make a FrameWnd in the dll , I am making a dll plugin for 3ds max

See more:

MFC

DLL

mainframe

I am coding for a max plugin(*.dlo), a .dll, I build a MFC regular Dll for it and run normally in max, but I can not build the CMainFrame on the dll.
I known the CWinApp::Run() didn't applied to the Dll, I read some papers about making MDI on dll on this forum,but failed when call:

AfxSetResourceHandle(hInstance);
               CSingleDocTemplate* pDocTemplate;
               pDocTemplate = new CSingleDocTemplate(
                            IDR_MAINFRAME,
                            RUNTIME_CLASS(CMFCAPPDoc),
                            RUNTIME_CLASS(CMainFrame),       // main SDI frame window
                            RUNTIME_CLASS(CMFCAPPView));
               CWinApp* app = AfxGetApp();      //no use because app = null why
               Interface* ip = GetCOREInterface();
               CFrameWnd* pMaxFrame = (CFrameWnd*)ip->GetMAXHWnd();
               CMFCAPPDoc*  pDoc  = (CMFCAPPDoc*)pDocTemplate->CreateNewDocument();
               CMainFrame* pFrame = (CMainFrame*)pDocTemplate->CreateNewFrame(pDoc, pMaxFrame);

               pDocTemplate->InitialUpdateFrame(pFrame,pDoc, TRUE);

And AfxGetApp() return NULL out of CWinApp class
so please help everyone?