You are using it wrong, it returns a BitmapData. So it needs to be:
BitmapData bitmapData;
Status ret = src->LockBits(new Rect(0, 0, srcWidth, srcHeight),
ImageLockMode::ImageLockModeRead | ImageLockMode::ImageLockModeWrite,
src->GetPixelFormat(),
&bitmapData);
if (ret != Ok) {
// Report error
//...
}
Not not skip error checking.