Background image becomes dark after adding watermark, need help.

I want to add text on bitmap,the following is the implementation.
After adding text watermark, I find text watermark is added on the
bitmap, while the bitmap is complete dark.The bitmap I used is not a
dark image. That is to say,generating bitmap only contain
watermark,not including original bitmap information.I still don't find
the bug to the function and do hope someone could give me some
clues,thanks in advance.

//pBitmap: the original bitmap
//BitmapNew: the bitmap created after processed the original bitmap
//iSize: text font size
//strText: text stuff
//color: text color
void AddTextWatermark(CBitmap *pBitmap,CBitmap &BitmapNew,int
iSize,LPCSTR strText,COLORREF color)
{
    CDC dcSrc,dcDst ;
        int nWidth, nHeight ;

        BITMAP pBitMap ;
        pBitmap->GetBitmap(&pBitMap) ;

     //FONT
     CFont textFont;
     textFont.CreatePointFont(iSize,strText);

        nWidthOld = pBitMap.bmWidth ;
        nHeightOld = pBitMap.bmHeight ;

         // Create DC
        dcSrc.CreateCompatibleDC((CDC*)NULL);
        dcDst.CreateCompatibleDC((CDC*)NULL);

        // Source Bitmap
        dcSrc.SelectObject(pBitmap);

        // New Bitmap
        BitmapNew.CreateCompatibleBitmap(&dcSrc,nWidth,nHeight);

        // add watermarker on Bitmap
        dcDst.SelectObject(&BitmapNew);
    dcDst.SelectObject(&textFont);
    dcDst.SetTextColor(color);
    dcDst.SetBkMode(TRANSPARENT);
    dcDst.TextOut(70,8,strText); //Position:(10,15)

        // Free Resource
       dcSrc.DeleteDC() ;
       dcDst.DeleteDC() ;
}