more than one Video Renderer, the get_FullScreenMode() always return E_NOTIMPL!

In my program there are two video render filters, one for local window and the other for remote. However, when I did the following:

IVideoWindow *pRemoteVideoRendererVW=NULL
hr = Graph.gcap.pFg->QueryInterface(IID_IVideoWindow, (void **) &pRemoteVideoRendererVW);

if (hr!=S_OK)
{
Log.Log(1,"IID_IVideoWindow failed %08x",hr);
return;
}

LONG lMode;
hr= pRemoteVideoRendererVW->get_FullScreenMode(&lMode);
if (hr!=S_OK)
{
Log.Log(1,"CCyklOneDlg::OnFullscreen get_FullScreenMode failed %08x",hr);
goto exit;
}

Everything went through without any error. Excepting the pRemoteVideoRendererVW returned by the QueryInterface() does not guarantee that it was the remote windows. It sometimes returns the local video windowns( randomly selected). Therefore I modified the code as following:

IBaseFilter *pVideoRenderer=NULL;
hr = Graph.gcap.pFg->FindFilterByName(L"RemoteVideoRenderer",(IBaseFilter **)&pVideoRenderer);

if (hr!=S_OK)
{
Log.Log(1,"Fullscreen failed to FindFilterByName: %08x",hr);
return;
}

hr = pVideoRenderer->QueryInterface(IID_IVideoWindow, (void **)&pRemoteVideoRendererVW);
if (hr!=S_OK)
{
Log.Log(1,"OFullscreen IID_IVideoWindow failed %08x",hr);
return;
}

if (!pRemoteVideoRendererVW)
{
Log.Log(1,"Fullscreen !m_pRemoteVideoRendererVW");
return ;
}

hr= pRemoteVideoRendererVW->get_FullScreenMode(&lMode);
if (hr!=S_OK)
{
Log.Log(1,"CCyklOneDlg::OnFullscreen get_FullScreenMode failed %08x",hr);
goto exit;
}

It again went through ok until the function get_FullScreenMode() which returned E_NOTIMPL! I really do not understand why it returned E_NOTIMPL as it was ok from the pervious codes excepting it return me different window render randomly. I am sure that the filter existed and had been added to the graph with the name. I have tried many many different ways but ended up the same result with the error returned(E_NOTIMPL) from the get_FullScreenMode(). Please anyone know what have I missed or done wrong Any suggestion please, thank you!

/Ben