VC中对话框程序不响应WM_CHAR WM_KEYUP \ WM_KEYDOWN消息

BOOL CMyTextDlg::PreTranslateMessage(MSG* pMsg) 
{
     // TODO: Add your specialized code here and/or call the base class
    if (pMsg->message == WM_KEYDOWN)
    {
    if( pMsg->wParam==8 )//pMsg->wParam的值就是对应的按键值
        messagebox("Backspace键按下了...");
        return TRUE;
    }
    else
    {
        return CDialog::PreTranslateMessage(pMsg);
    }
}

if (pMsg->message == WM_KEYDOWN)
{
    if( GetKeyState(VK_SHIFT)<0 )    //shift键是否按下
    {
        if( 187==pMsg->wParam )    //pMsg->wParam的值就是对应的按键值
            messagebox(" + 号键按下了...");
    }
        return TRUE;
}