为啥代码没错却不显示Bmp图片？

为什么代码没错却不显示Bmp图片？？？？？？
代码如下，运行窗体没有错误，窗体正常显示，只是不显示Bmp图片。

C/C++ code

switch(message){case WM_CREATE:    g_hbmBall = LoadBitmap(GetModuleHandle(NULL),MAKEINTRESOURCE(IDB_BALL));    if(g_hbmBall == NULL)        MessageBox(hwnd,TEXT("Couldn't load bitmap!"),TEXT("Error"),MB_OK | MB_ICONERROR);    break;case WM_COMMAND:    wmId = LOWORD(wParm);    switch (wmId)    {    case IDM_ABOUT:        DialogBox(hInst,MAKEINTRESOURCE(IDD_ABOUTBOX),hwnd,AboutProc);        break;    case IDM_QUIT:        DestroyWindow(hwnd);        break;    default:        return DefWindowProc(hwnd, message, wParm, lParam);    }break;case WM_PAINT:    {    PAINTSTRUCT ps;    BITMAP bm;    HDC hdc = BeginPaint(hwnd, &ps);            HDC hdcMem = CreateCompatibleDC(hdc);            SelectObject(hdcMem,g_hbmBall);            GetObject(g_hbmBall, sizeof(bm), &bm);            BitBlt(hdc, 0, 0, bm.bmWidth, bm.bmHeight, hdcMem,0, 0, SRCCOPY);            DeleteDC(hdcMem);            EndPaint(hwnd, &ps);    break;}case WM_DESTROY:    DeleteObject(g_hbmBall);    PostQuitMessage(0);    break;default:    return DefWindowProc(hwnd,message,wParm,lParam);