[2005] Problem with BitBlt from Bitmap to Bitmap

Hi.

Can someone tell me why this doesn't work?
I would expect the end result to be all red, but nothing happens.
If I remove the source bitmap and graphics object and just use "hdcSrc=GetDC(0)" then I get a screenshot, so I know the BitBlt function works.
It appears that the BitBlt function can't copy from one memory image to another.

So, can anyone answer this:
Are there any problems BitBlt'ing two memory images? Or does it have to be real physical devicecontexts?

VB Code:

Dim bmpDst, bmpSrc As Bitmap
        Dim grpDst, grpSrc As Graphics
        Dim hdcDst, hdcSrc As IntPtr
 
        bmpDst = New Bitmap(Panel1.ClientRectangle.Width, Panel1.ClientRectangle.Height)
        bmpSrc = New Bitmap(Panel1.ClientRectangle.Width, Panel1.ClientRectangle.Height)
 
        grpDst = Graphics.FromImage(bmpDst)
        grpSrc = Graphics.FromImage(bmpSrc)
 
        grpDst.Clear(Color.Black)
        grpSrc.Clear(Color.Red)
        grpSrc.Flush()
 
        hdcDst = grpDst.GetHdc
        hdcSrc = grpSrc.GetHdc
 
        Win32.Declarations.BitBlt(hdcDst, 0, 0, bmpDst.Width, bmpDst.Height, hdcSrc, 0, 0, Win32.Constants.BitBltConstants.SRCCOPY)
 
        grpSrc.ReleaseHdc(hdcSrc)
        grpDst.ReleaseHdc(hdcDst)
 
        grpSrc.Dispose()
        grpDst.Dispose()
 
        e.Graphics.DrawImage(bmpDst, 0, 0)
 
        bmpDst.Dispose()
        bmpSrc.Dispose()

Thanks