为何显示黑乎乎的一片，chick!!!!!!!

void CHeQiQiView::OnDraw(CDC* pDC)
{
CRect rt;
GetClientRect(rt);

HBITMAP hbmp=LoadBitmap(AfxGetApp()->m_hInstance, (LPCTSTR)IDB_BITMAP);

HDC memBufDC=CreateCompatibleDC(pDC->m_hDC);
HDC memSrcDC=CreateCompatibleDC(pDC->m_hDC);

HBITMAP hbmpOld=(HBITMAP)SelectObject(memSrcDC,hbmp);

for(int i=0;i<600;i+=15)
{
BitBlt(memBufDC, i, 0, 15, 15,memSrcDC,0,0,SRCCOPY);
}
HBITMAP hBufBmp = CreateCompatibleBitmap(pDC->m_hDC, rt.right, rt.bottom-100);
HBITMAP hOldBufBmp = (HBITMAP)SelectObject(memBufDC, hBufBmp);

BitBlt(pDC->m_hDC, 0, 0, rt.right, rt.bottom-100, memBufDC, 0, 0, SRCCOPY);

SelectObject(memSrcDC,hbmpOld);
SelectObject(memBufDC, hOldBufBmp);
DeleteObject(hBufBmp);
DeleteDC(memBufDC);
}

显示的结果，是显示黑乎乎的一片，这出错在那儿，能给我看一下吗。3x