Baclk background for images saved from ListView

I'm using this code to extract the images in the LargeImageList member of a
ListView. This images appears fine int he ListView while the application
runs, but when extracted they are coming out with a black background. I'm
not sure what I'm doing wrong, maybe some extra layer I need to extract/add.
I've tried all formats, (GIF,JPEG,PNG) and they all have the same problem.

int nCount = lstlanguages.Items.Count;
string strFilename;
for (int nImage = 0; nImage < nCount; nImage++)
{
strFilename = ("\\FFSDISK\\BMP" + (nImage+1).ToString() + ".bmp");
lstlanguages.LargeImageList.Images[nImage].Save(strFilename,
System.Drawing.Imaging.ImageFormat.Bmp);
}

Thanks,
Alain