Save drawing from PictureBox

[arsmakman]

Hey there,

I'm trying to save the lines I drew in a PictureBox as a bitmap, but it just returns blank images...

This is the code I have now:

'Draw a grid on PictureBox named draw
For x As Integer = 0 To bWidth
    For y As Integer = 0 To bHeight
        draw.CreateGraphics.DrawLine(Pens.Black, New Point(xStart + x * bScale, yStart), New Point(xStart + x * bScale, yStart + ySize))
        draw.CreateGraphics.DrawLine(Pens.Black, New Point(xStart, yStart + y * bScale), New Point(xStart + xSize, yStart + y * bScale))
    Next
Next
 
'Save as BMP-file
Dim bmp As New Bitmap(draw.Width, draw.Height)
draw.DrawToBitmap(bmp, New Rectangle(0, 0, draw.Width, draw.Height))
bmp.Save("D:\output.png", Imaging.ImageFormat.Png)
bmp.Dispose()

The file output.png in now a blank image, the size of the PictureBox. If I try to save the entire form with Me.DrawToBitmap(), I get the form itself but the PictureBox is blank, while the grid is visible on screen.

WHAT DO?!

Thanks for your help,
Alexander.