สอบถามเรื่องการทำ session timeout ครับ รบกวนช่วยดูให้หน่อยครับ

 Response.Cache.SetCacheability(HttpCacheability.NoCache)
If IsPostBack = False Then
Session("Reset") = True
                Dim config As Configuration = WebConfigurationManager.OpenWebConfiguration("~/Web.Config")
                Dim section As SessionStateSection = DirectCast(config.GetSection("system.web/sessionState"), SessionStateSection)
                Dim timeout As Integer = CInt(section.Timeout.TotalMinutes) * 1000 * 60
                ClientScript.RegisterStartupScript(Me.GetType(), "SessionAlert", "SessionExpireAlert(" & timeout & ");", True)



<script type="text/javascript">
function SessionExpireAlert(timeout) {
    var seconds = timeout / 1000;
    document.getElementsByName("secondsIdle").innerHTML = seconds;
    document.getElementsByName("seconds").innerHTML = seconds;
    setInterval(function () {
        seconds--;
        document.getElementById("seconds").innerHTML = seconds;
        document.getElementById("secondsIdle").innerHTML = seconds;
    }, 1000);
    setTimeout(function () {
        //Show Popup before 20 seconds of timeout.
        $find("mpeTimeout").show();
    }, timeout - 20 * 1000);
    setTimeout(function () {
        window.location = "Login.aspx";
    }, timeout);
};
function ResetSession() {
    //Redirect to refresh Session.
    window.location = window.location.href;
}
</script>

<h5>Session Idle:&nbsp;<span id="secondsIdle"></span>&nbsp;seconds.</h5>
<asp:LinkButton ID="lnkFake" runat="server" />
<asp:ModalPopupExtender ID="mpeTimeout" BehaviorID ="mpeTimeout" runat="server" PopupControlID="pnlPopup" TargetControlID="lnkFake"
    OkControlID="btnYes" CancelControlID="btnNo" BackgroundCssClass="modalBackground" OnOkScript = "ResetSession()">
</asp:ModalPopupExtender>
<asp:Panel ID="pnlPopup" runat="server" CssClass="modalPopup" Style="display: none">
    <div class="header">
        Session Expiring!
    </div>
    <div class="body">
        Your Session will expire in&nbsp;<span id="seconds"></span>&nbsp;seconds.<br />
        Do you want to reset?
    </div>
    <div class="footer" align="right">
        <asp:Button ID="btnYes" runat="server" Text="Yes" CssClass="yes" />
        <asp:Button ID="btnNo" runat="server" Text="No" CssClass="no" />
    </div>
</asp:Panel>

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        System.Threading.Thread.CurrentThread.CurrentCulture = New System.Globalization.CultureInfo("en-GB")


        Response.Cache.SetCacheability(HttpCacheability.NoCache)
        If Session("USERID") <> Nothing Then

            If IsPostBack = False Then
                
                Dim V As String = Session("view")
                Dim P As String = Session("Postpone")
                Dim A As String = Session("Approve")
                Dim SP As String = Session("SP")

                If Session("view") = Nothing And Session("Postpone") = Nothing And Session("Approve") = Nothing Then
                    Panel13.Visible = False
                    Panel10.Visible = True
                    ImbEdit.Visible = True
                    imbNew.Visible = True
                    ImbEditship.Visible = False
                    Panel5.Visible = False
                    Panel3.Visible = False
                    Panel4.Visible = False
                    Panel6.Visible = False
                    Panel7.Visible = False
                    Panel8.Visible = False
                    Panel9.Visible = False
                    Panel11.Visible = False
                    Panel12.Visible = False
                    btnRelease.Visible = False
                    btnADD.Visible = False
                    btnSave.Visible = False
                    Imagenew.Visible = False

                    lblAD_ADDR.Visible = False
                    lblAD_CITY.Visible = False
                    lblAD_LINE1.Visible = False
                    lblAD_LINE3.Visible = False
                    lblAD_LINE4.Visible = False
                    lblAD_LINE2Bill.Visible = False
                    lblAD_LINE3Bill.Visible = False
                    lblAD_NAME.Visible = False
                    lblAD_COUNTRY.Visible = False

                    lblad_phone.Visible = False
                    lblad_phone0.Visible = False

                    lblAD_ADDR0.Visible = False
                    lblAD_CITY0.Visible = False
                    lblAD_LINE2.Visible = False
                    lblAD_NAME0.Visible = False
                    lblAD_COUNTRY0.Visible = False

                    lblAD_STATE.Visible = False
                    lblAD_ZIP0.Visible = False
                    lblAD_ZIP.Visible = False
                    lblAD_STATE0.Visible = False

                    btnReturn.Visible = False
                    cbPackage.Items.Insert(0, New ListItem("--select--", ""))
                    cbPackage.SelectedValue = cbPackage.Items(0).Value
                    cbApprove.Visible = False

                    Dim dtc As DataSet
                    dtc = gcurren()
                    With Me.cbCurr
                        .Items.Clear()
                        .DataSource = dtc
                        .DataTextField = "cu_curr"
                        .DataValueField = "cu_curr"
                        .DataBind()

                    End With

                End If

                If A = "Approve" Then
                    If SP = "SP" Then
                        Dim wf_doc As String = Session("wf_doc")
                        ViewSaleInvoid(sender, e)

                        Panel10.Visible = True
                        ImbEdit.Visible = False
                        imbNew.Visible = False
                        ImbEditship.Visible = True
                        btnReturn.Visible = True


                        Panel6.Visible = False
                        lblappove.Visible = False
                        cbApprove.Visible = False
                        btncancle.Visible = False
                        Label109.Visible = False


                    Else
                        Dim wf_doc As String = Session("wf_doc")
                        ViewSaleInvoid(sender, e)

 
                        Panel10.Visible = True
                        ImbEdit.Visible = False
                        imbNew.Visible = False
                        ImbEditship.Visible = False
                        btnReturn.Visible = True

                    End If
                End If

                If P = "Postpone" Then
                    ImbEditship.Visible = False
                    Dim Doc As String = Session("wf_doc")
                    ViewSaleInvoid(sender, e)
                    btnReturn.Visible = True

                End If

            End If



            If rdoReyes.Checked = True Then
                lblBOILocal.Text = "ใบขนสุทธินำกลับ"
                lblBOIImport.Text = "ใบขนสุทธินำกลับ"
                lblNONBOILocal.Text = "ใบขนปากระวาง"
                lblTexedImport.Text = "(นำเข้าโดยเสียภาษี)"
            ElseIf rdoReno.Checked = True Then


                lblBOILocal.Text = ""
     
                lblNONBOILocal.Text = "ใบขนปากระวาง"


                lblBOIImport.Text = ""

                lblTexedImport.Text = "(นำเข้าโดยเสียภาษี)"
            End If

            amountfooter()

        Else
            Response.Redirect("Login.aspx")
        End If

    End Sub