OpenClipboard

Hi, I have the following code:
BOOL CVideo::CaptureFrame()
{

    HBITMAP m_hBmp = NULL;
    CBitmap m_bmp; //bitmap object

   capGrabFrame(hWndC); // macro that sample a single frame from the
                        // camera.
   capEditCopy(hWndC);
   EmptyClipboard();// simple macro that edit a copy of the frame.
   OpenClipboard();

// m_hBmp is a Handle to Bitmap.
   m_hBmp = (HBITMAP)::GetClipboardData(CF_BITMAP);
   CloseClipboard();

   m_bmp.Detach(); //cleaning the bitmap.
   m_bmp.Attach(m_hBmp); //connecting the bitmap throw the handle.

    return true;
}

I call this function when i want to capture a frame. But, when I call
OpenClipboar, an assertion failure window is pop out, and the program
fails.
Can anybody please explain why the OpenClipboard function fails?
I want to save a .bmp file. I could save a avi frame using the
following statements:
    capFileSetCaptureFile(hWndC, "c:\\myCapturedFrame");
    capCaptureSingleFrameOpen(hWndC);
    capCaptureSingleFrame(hWndC);
    capCaptureSingleFrameClose(hWndC);

but that pice of code generates an myCaptureFrame.avi, but I need a
..bmp file.
Thanks for your time.