手动创建的实列显示不出来？

从CWnd派生的CEditTrack，用如下创建的实列，可是显示不出来，什么也看不到。m_EditTrack.Create( _T("EDITTRACK"),NULL,
                    WS_VISIBLE|WS_CHILD|WS_TABSTOP,
                    CRect( 50, 400,800,250 ),this,0
                  ); CEditTrack是这样写的：class CEditTrack : public CWnd
{
protected:
DECLARE_DYNCREATE(CEditTrack)public:
CEditTrack(){
              RegisterWindowClass();
         } virtual ~CEditTrack(); virtual BOOL Create( LPCTSTR lpszClassName, 
                   LPCTSTR   lpszWindowName, DWORD dwStyle, 
                   const RECT& rect,CWnd* pParentWnd, 
                   UINT nID, CCreateContext* pContext = NULL)
         {
          //这里我什么也没写
          return CWnd::Create( lpszClassName,lpszWindowName,
                               dwStyle,rect,pParentWnd,nID,pContext );
         } BOOL RegisterWindowClass()
         {
              WNDCLASS wndcls;
              HINSTANCE hInst = AfxGetInstanceHandle();              if (!(::GetClassInfo(hInst, EDITTRACK_CLASSNAME, &wndcls)))
              {
                  wndcls.style  = CS_DBLCLKS | CS_HREDRAW | CS_VREDRAW;
                  wndcls.lpfnWndProc      = ::DefWindowProc;
                  wndcls.cbClsExtra       = wndcls.cbWndExtra = 0;
                  wndcls.hInstance        = hInst;
                  wndcls.hIcon            = NULL;
               wndcls.hCursor=AfxGetApp()->LoadStandardCursor (IDC_ARROW);
               wndcls.hbrBackground    = (HBRUSH) (COLOR_3DFACE + 1);
               wndcls.lpszMenuName     = NULL;
               wndcls.lpszClassName    = EDITTRACK_CLASSNAME;               return AfxRegisterClass(&wndcls));
               }              return TRUE;
         }private:
void DrawScale( CDC *lpDC );
void DrawGrade( CDC *lpDC,RECT rect,bool UpDown );
void DrawRuler( CDC *lpDC );
void DrawSeparateLine( CDC *lpDC );
void DrawLinePos( CDC *lpDC );
private:
void DrawRect(CDC *lpDC,RECT rect,int Color,bool Selected);
void DrawTrack( CDC *lpDC,enumTrack TrackFlag );protected:
//{{AFX_MSG(CEditTrack)
afx_msg void OnPaint();
afx_msg void OnSize(UINT nType, int cx, int cy);
afx_msg void OnLButtonDown(UINT nFlags, CPoint point);
afx_msg void OnLButtonUp(UINT nFlags, CPoint point);
afx_msg void OnMouseMove(UINT nFlags, CPoint point);
//}}AFX_MSG DECLARE_MESSAGE_MAP()}