Forms Data Controls :: Printing The Gridview In Page?

i am printing girdview on clicking on button

[Code]....

Public Shared Sub PrintWebControl(ByVal ctrl As Control, ByVal Script As String)
'dim StringBuilder sb = new StringBuilder()
Dim sb As StringBuilder = New StringBuilder()
Dim stringWrite As IO.StringWriter = New IO.StringWriter(sb)
Dim htmlWrite As System.Web.UI.HtmlTextWriter = New System.Web.UI.HtmlTextWriter(stringWrite)
If TypeOf ctrl Is WebControl Then
Dim w As Unit = New Unit(100, UnitType.Percentage)
CType(ctrl, WebControl).Width = w
End If
Dim pg As Page = New Page()
pg.EnableEventValidation = False
pg.EnableViewState = False
pg.MaintainScrollPositionOnPostBack = False
If Script <> String.Empty Then
pg.ClientScript.RegisterStartupScript(pg.GetType(), "PrintJavaScript", Script)
End If
Dim frm As HtmlForm = New HtmlForm()
pg.Controls.Add(frm)
frm.Attributes.Add("runat", "server")
frm.Controls.Add(ctrl)
pg.DesignerInitialize()
pg.RenderControl(htmlWrite)
Dim strHTML As String = stringWrite.ToString()
HttpContext.Current.Response.Clear()
HttpContext.Current.Response.Write(strHTML)
HttpContext.Current.Response.Write("<script>window.print();</script>")
HttpContext.Current.Response.End()
End Sub

I get the error at line: pg.RenderControl(htmlWrite);

I tried setting the Enable Event Validation to false on the page but that didnt work..