ATL control display image with Bitblt SRCAND not correct in word 2013

I created a ATL project with following code:

LRESULT OnCreate(UINT /*uMsg*/, WPARAM /*wParam*/, LPARAM /*lParam*/, BOOL& /*bHandled*/)
{
    const LONG_PTR exStyle = GetWindowLongPtr(GWL_EXSTYLE);
    SetWindowLongPtr(GWL_EXSTYLE, exStyle | WS_EX_TRANSPARENT);
    return 0;
}

HRESULT OnDrawAdvanced(ATL_DRAWINFO& di)
{
    RECT& rc = *(RECT*)di.prcBounds;

    CImage imgx;
    imgx.Load(_T("C:\\image.jpg"));
    imgx.StretchBlt(di.hdcDraw, rc.left, rc.top, rc.right, rc.bottom, 0,0,imgx.GetWidth(),imgx.GetHeight(), SRCAND);

    return S_OK;
}