Module PushSourceD3D.dll, 2 objects left active!

Hi, I have modified the PushSource Desktop filter for my own purpose (converting an offscreen rendered D3D surface into a video stream). Therefore I added an interface to my filter so I can pass it a pointer to my IDirect3DSurface9. By the point, it works "fine", since it correctly shows me the surface as a video stream. But when I close my test application I get a "2 objects left active!" error, here the complete error message: "Executable: PSD3DFilterTest.exe Pid e08 Tid ef0. Module PushSourceD3D.dll, 2 objects left active! At line 317 of C:\DX90SDK\Samples\C++\DirectShow\BaseClasses\dllentry.cpp" This error appeared first when I introduce my ID3DSurf interface, but don''t know what I''ve forgotten. I render the out pin of my filter using RenderEx(pOutputPin, AM_RENDEREX_RENDERTOEXISTINGRENDERERS, NULL). Where can be my problem? Thanks in advance.. Here the main parts of my CPushSourceD3D class:

//////////////////////////////////////

//A part of my PushSourceD3D.hpp file

//////////////////////////////////////


class CPushSourceD3D :  public CSource, public ID3DSurf 
{
	friend class CPushPinD3D;
private:
    // Constructor is private because you have to use CreateInstance

    CPushSourceD3D(IUnknown *pUnk, HRESULT *phr);
    ~CPushSourceD3D();

    CPushPinD3D *m_pPin;

    //ID3DSurf interface

    CCritSec m_csShared;		//Protects shared data

    LPDIRECT3DSURFACE9 m_pD3DSurface;	//D3D Source Surface

	
public:
	
    static CUnknown * WINAPI CreateInstance(IUnknown *pUnk, HRESULT *phr);  

    // Reveals ID3DSurf

    STDMETHODIMP NonDelegatingQueryInterface(REFIID riid, void ** ppv);

    DECLARE_IUNKNOWN;

	//Get the current surface pointed by the ID3DSurf interface

	STDMETHODIMP get_D3DSurface(LPDIRECT3DSURFACE9 *pD3DSurface9)
	{
		if (!pD3DSurface9) return E_POINTER;
		CAutoLock lock(&m_csShared);
		*pD3DSurface9 = m_pD3DSurface;
		//MessageBox(NULL, TEXT("get_D3DSurface"), TEXT("Surface returned"), MB_OK);

		return S_OK;
	}

	//Set the surface to be pointed by the ID3DSurf interface

	STDMETHODIMP set_D3DSurface(LPDIRECT3DSURFACE9 pD3DSurface9)
	{
		if (!pD3DSurface9) return E_POINTER;
		CAutoLock lock(&m_csShared);
		m_pD3DSurface = pD3DSurface9;
		//MessageBox(NULL, TEXT("select_D3DSurface"), TEXT("Surface set"), MB_OK);

		return S_OK;
	}

};

//////////////////////////////////////

//A part of my PushSourceD3D.cpp file

//////////////////////////////////////


/**********************************************
 *
 *  CPushSourceD3D Class
 *
 **********************************************/

CPushSourceD3D::CPushSourceD3D(IUnknown *pUnk, HRESULT *phr)
           : CSource(NAME("PushSourceD3D"), pUnk, CLSID_PushSourceD3D)
{
    // The pin magically adds itself to our pin array.

    m_pPin = new CPushPinD3D(phr, this);
	
	m_pD3DSurface = NULL;

	if (phr)
	{
		if (m_pPin == NULL)
			*phr = E_OUTOFMEMORY;
		else
			*phr = S_OK;
	}  
}


CPushSourceD3D::~CPushSourceD3D()
{
    delete m_pPin;
    m_pD3DSurface = NULL;
}


CUnknown * WINAPI CPushSourceD3D::CreateInstance(IUnknown *pUnk, HRESULT *phr)
{
    CPushSourceD3D *pNewFilter = new CPushSourceD3D(pUnk, phr );

	if (phr)
	{
		if (pNewFilter == NULL) 
			*phr = E_OUTOFMEMORY;
		else
			*phr = S_OK;
	}
    return pNewFilter;

}


//

// NonDelegatingQueryInterface

//

// Reveals ID3DSurf interface

//

STDMETHODIMP CPushSourceD3D::NonDelegatingQueryInterface(REFIID riid, void **ppv)
{
    CheckPointer(ppv,E_POINTER);

    if (riid == IID_ID3DSurf) {
        //return GetInterface((ID3DSurf *) this, ppv);

		return GetInterface(static_cast<ID3DSurf*>(this), ppv);

    } else {
        return CSource::NonDelegatingQueryInterface(riid, ppv);
    }

} // NonDelegatingQueryInterface