Why the image loaded in temporary is not correct?

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C++

MFC

ActiveX

When i load image into temporary DC. the pixel[15,50]is green on the control .But in the temporary dc, It is [15,80].

It as if my image is go down in temp DC.
I don't now why?.
Could anyone help me?
my first control, use this:

void myfunction(CPoint point,CDC *dc)
{      CDC dcMem;
	dcMem.CreateCompatibleDC(dc);
	dcMem.SelectObject(bmpCOM);
	HDC hdcMem=dcMem;
	COLORREF clr= GetPixel(hdcMem,point.x,point.y);
}

My Second control, i click directly onn control with LBUTTONDOWN.

void CDirectClickCtrl::OnLButtonDown(UINT nFlags, CPoint point)
{
	HWND hWnd=this->GetSafeHwnd();
	COLORREF clr=GetPixel(::GetDC(hWnd),point.x,point.y);

	COleControl::OnLButtonDown(nFlags, point);
}