Creating a picture in a memory bitmap

I am trying to draw a picture in a memory bitmap then bitblt it back to a picture box but all I get is a black image, does anyone have any idea what i'm doing wrong.

Code:

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testhnd = frmTest.PicTest.hDC
 ' Create a device context to hold the image.
    mem_dc = CreateCompatibleDC(testhnd)
         
    hBmp = CreateCompatibleBitmap(mem_dc,  frmTest.PicTest.Width, frmTest.PicTest.Height)
         
' Select the bitmap into the device context.
      SelectObject mem_dc, hBmp

'Set colours
    res = SetBkMode(mem_dc, OPAQUE)
    res = SetBkColor(mem_dc, glWHITE)

'set pen
    lCustomPen = CreatePen(PS_SOLID, 1, glBLACK)
    res = SelectObject(mem_dc, lCustomPen)
    SelectObject mem_dc, GetStockObject(WHITE_BRUSH)

' Draw a rectangle
    res = Rectangle(mem_dc, 10,10,80,80)

' Copy the bitmap into picResult.
    BitBlt testhnd, 0, 0, frmTest.PicTest.Width,  frmTest.PicTest.Height, _
            mem_dc, 0, 0, SRCCOPY

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