CWnd求助

如下代码，为何不能正确显示?多谢指教CWnd m_ClockTime;
m_ClockTime.Create(NULL,"time",WS_BORDER|WS_CHILD|WS_VISIBLE,CRect(TabClient.left+10,TabClient.top+30,TabClient.left+70,TabClient.top+50),GetDlgItem(IDC_CLOCKTYPE),IDC_CLOCKTIME);HDC hwnd = m_ClockTime.GetDC()->GetSafeHdc();
HDC hmem = CreateCompatibleDC(hwnd);
HBITMAP hbg;
BITMAP bm;
CRect rc;
m_ClockTime.GetClientRect(&rc);
hbg = LoadBitmap(AfxGetInstanceHandle(),MAKEINTRESOURCE(IDB_BACKGROUND));
GetObject(hbg,sizeof(bm),&bm);
SelectObject(hmem,hbg);
StretchBlt(hwnd,0,0,rc.right-rc.left,rc.bottom-rc.top,hmem,0,0,bm.bmWidth,bm.bmHeight,SRCCOPY);
结果没有显示出图像IDB_BACKGROUND,而且如下代码也不做任何显示，为何？
m_ClockTime.GetDC()->TextOut(5,5,"Text");
m_ClockTime.GetDC()->MoveTo(0,0);
m_ClockTime.GetDC()->LineTo(5,5);