how to convert a panel form into a PDF form? - vb.net

Question

net 2010 and I have the following code which brings the panel and its contents to a printer but every time I try to convert the panel into a PDF form the pd.Print() in the button click always returns a nullreferencedunhandled any idea on ho to fix this??
thanks
Public Class Form1
Dim img As Bitmap
Dim WithEvents pd As PrintDocument
'Returns the Form as a bitmap
Function CaptureForm1() As Bitmap
Dim g1 As Graphics = Me.CreateGraphics()
Dim MyImage = New Bitmap(Me.ClientRectangle.Width, (Me.ClientRectangle.Height), g1)
Dim g2 As Graphics = Graphics.FromImage(MyImage)
Dim dc1 As IntPtr = g1.GetHdc()
Dim dc2 As IntPtr = g2.GetHdc()
BitBlt(dc2, 0, 0, Me.ClientRectangle.Width, (Me.ClientRectangle.Height), dc1, 0, 0, 13369376)
g1.ReleaseHdc(dc1)
g2.ReleaseHdc(dc2)
'saves image to c drive just, u can comment it also
'MyImage.Save("c:\abc.bmp")
Return MyImage
End Function
<DllImport("gdi32.DLL", EntryPoint:="BitBlt", _
SetLastError:=True, CharSet:=CharSet.Unicode, _
ExactSpelling:=True, _
CallingConvention:=CallingConvention.StdCall)> _
Private Shared Function BitBlt(ByVal hdcDest As IntPtr, ByVal nXDest As Integer, ByVal nYDest As Integer, ByVal nWidth As Integer, ByVal nHeight As Integer, ByVal hdcSrc As IntPtr, ByVal nXSrc As Integer, ByVal nYSrc As Integer, ByVal dwRop As System.Int32) As Boolean
' Leave function empty - DLLImport attribute forwards calls to MoveFile to
' MoveFileW in KERNEL32.DLL.
End Function
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
'img = CaptureForm1()
'pd = New PrintDocument
'pd.Print()
Dim PrintDialog1 As New PrintDialog()
PrintDialog1.Document = pd
Dim result As DialogResult = PrintDialog1.ShowDialog()
If (result = DialogResult.OK) Then
pd.Print()
End If
End Sub
'this method will be called each time when pd.printpage event occurs
Sub pd_PrintPage(ByVal sender As Object, ByVal e As PrintPageEventArgs) Handles pd.PrintPage
Dim x As Integer = e.MarginBounds.X
Dim y As Integer = e.MarginBounds.Y
e.Graphics.DrawImage(img, x, y)
e.HasMorePages = False
End Sub
End Class