Protected Sub Excel_Button_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Excel_Button.Click

        Dim GridView2 As New GridView
        GridView2 = GridView1
        GridView2.AllowPaging = False
        GridViewSortExpression = Session("SortExpression")       
        myAdsDataTable = Session("SalesTicketDataTable")
        GridView2.DataSource = SortDataTable(myAdsDataTable, False)
        GridView2.DataBind()

        Export("SalesTicketExport.xls", GridView2)

    End Sub


    Public Shared Sub Export(ByVal fileName As String, ByVal gv As GridView)
        HttpContext.Current.Response.Clear()
        HttpContext.Current.Response.AddHeader("content-disposition", String.Format("attachment; filename={0}", fileName))
        HttpContext.Current.Response.ContentType = "application/ms-excel"
        Dim sw As IO.StringWriter = New IO.StringWriter
        Dim htw As HtmlTextWriter = New HtmlTextWriter(sw)
        '  Create a form to contain the grid
        Dim table As Table = New Table
        table.GridLines = gv.GridLines
        '  add the header row to the table
        If (Not (gv.HeaderRow) Is Nothing) Then
            PrepareControlForExport(gv.HeaderRow)
            table.Rows.Add(gv.HeaderRow)
        End If
        '  add each of the data rows to the table
        For Each row As GridViewRow In gv.Rows
            PrepareControlForExport(row)
            table.Rows.Add(row)
        Next
        '  add the footer row to the table
        If (Not (gv.FooterRow) Is Nothing) Then
            PrepareControlForExport(gv.FooterRow)
            table.Rows.Add(gv.FooterRow)
        End If
        '  render the table into the htmlwriter
        table.RenderControl(htw)
        '  render the htmlwriter into the response
        HttpContext.Current.Response.Write(sw.ToString)
        HttpContext.Current.Response.End()
    End Sub

    ' Replace any of the contained controls with literals
    Private Shared Sub PrepareControlForExport(ByVal control As Control)
        Dim i As Integer = 0
        Do While (i < control.Controls.Count)
            Dim current As Control = control.Controls(i)
            If (TypeOf current Is LinkButton) Then
                control.Controls.Remove(current)
                control.Controls.AddAt(i, New LiteralControl(CType(current, LinkButton).Text))
            ElseIf (TypeOf current Is ImageButton) Then
                control.Controls.Remove(current)
                control.Controls.AddAt(i, New LiteralControl(CType(current, ImageButton).AlternateText))
            ElseIf (TypeOf current Is HyperLink) Then
                control.Controls.Remove(current)
                control.Controls.AddAt(i, New LiteralControl(CType(current, HyperLink).Text))
            ElseIf (TypeOf current Is DropDownList) Then
                control.Controls.Remove(current)
                control.Controls.AddAt(i, New LiteralControl(CType(current, DropDownList).SelectedItem.Text))
            ElseIf (TypeOf current Is CheckBox) Then
                control.Controls.Remove(current)
                control.Controls.AddAt(i, New LiteralControl(CType(current, CheckBox).Checked))
            ElseIf (TypeOf current Is Image) Then
                control.Controls.Remove(current)
            End If
            If current.HasControls Then
                PrepareControlForExport(current)
            End If
            i = (i + 1)
        Loop
    End Sub

Protected Sub GridView1_Sorting1(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewSortEventArgs) Handles GridView1.Sorting

        GridViewSortExpression = e.SortExpression
        Session("SortExpression") = e.SortExpression       
        myAdsDataTable = Session("SalesTicketDataTable")
        Dim pageIndex As Integer = GridView1.PageIndex
        GridView1.DataSource = SortDataTable(myAdsDataTable, False)
        GridView1.DataBind()
        GridView1.PageIndex = pageIndex

    End Sub

GridView1.AllowPaging = False

        GridViewSortExpression = Session("SortExpression")
        myAdsDataTable = Session("SalesTicketDataTable")
        Dim pageIndex As Integer = GridView1.PageIndex
        GridView1.DataSource = SortDataTable(myAdsDataTable, False)
        GridView1.DataBind()
        GridView1.PageIndex = pageIndex
        Export("SalesTicketExport1.xls", GridView1)
        GridView1.AllowPaging = True