Gridview Print Page coming blank

Gridview Print PAge coming blank 

for below code 

but if I  comment 

 GRDV.AllowPaging = False

        GRDV .DataBind()  this code then it page is not blank 

so please help me .. I want to print complete Gridview

Code  is : 

 Protected Sub PrintAllPages()

       GRDV.AllowPaging = False

        GRDV .DataBind()

        Dim Title1 As String = SATitle.Text

        Dim Title2 As String = SAtitle1.Text

        Dim sw As New StringWriter()

        Dim hw As New HtmlTextWriter(sw)

        StudentAssignmentgridview.RenderControl(hw)

        Dim gridHTML As String = sw.ToString().Replace("""", "'") _

             .Replace(System.Environment.NewLine, "")

        Dim sb As New StringBuilder()

        sb.Append("<script type = 'text/javascript'>")

        sb.Append("window.onload = new function(){")

        sb.Append("var printWin = window.open('', '', 'left=0")

        sb.Append(",top=0,width=1000,height=1000,status=0');")

        sb.Append("printWin.document.write(""")

              sb.Append(gridHTML)

        sb.Append(""");")

        sb.Append("printWin.document.close();")

        sb.Append("printWin.focus();")

        sb.Append("printWin.print();")

        sb.Append("printWin.close();};")

        sb.Append("</script>")

   ClientScript.RegisterStartupScript(Me.[GetType](), "gridview", sb.ToString())

        ' GRDV.AllowPaging = True

        ' GRDV.DataBind()