modal popup using AJAX CONTROL TOOLKIT WHICH IS NOT DISPLAYED

<asp:Button ID="btn_lancer" Text="lancer" runat="server" />
    <%--popup superieur--%>
                <asp:Panel ID="PnlMsgAlert" runat="server" Visible="false" Style="display: none; height: 500;
                width: 500; background-color: #D3D3D3;">
                <div  id="div1"  runat="server">
                <asp:Label ID="lbl_message" runat="server" Text="Vous devez alertez tous les conducteurs"> </asp:Label>
                     <asp:Button ID="btnAlertOK" runat="server" Text="Oui" CssClass="cBtnPopup"  />
                    <br />
                </div>
            </asp:Panel>

            <asp:Button ID="btn_alert" runat="Server" Style="display: none" />

            <Ajax:ModalPopupExtender ID="popPopupAlert" PopupControlID="PnlMsgAlert" TargetControlID="btn_alert"  runat="server">
            </Ajax:ModalPopupExtender>
            <%--popup inferieur--%>
            <asp:Panel ID="PnlMsg" runat="server" Visible="false" Style="display: none; height: 500;
                width: 500; background-color: #D3D3D3;">
                <div id="div2"  runat="server">
                <asp:Label ID="lbMsg" runat="server" Text="Voulez-vous lancer la SESR même si le nombre des inscrits à  est en dessous de seuil"> </asp:Label>

                     <asp:Button ID="btnNon" runat="server" Text="Non" CssClass="cBtnPopup" />
                     <asp:Button ID="btnOui" runat="server" Text="Oui" CssClass="cBtnPopup"  />
                    <br />
                </div>
            </asp:Panel>

            <asp:Button ID="btnInvisible" runat="Server" Style="display: none" />

            <Ajax:ModalPopupExtender ID="popPopup"  runat="server" PopupControlID="PnlMsg" TargetControlID="btnInvisible" CancelControlID="btnInvisible">
            </Ajax:ModalPopupExtender>
            <%--unused--%>
    <%--<Ajax:ConfirmButtonExtender ID="cbe"  runat="server" TargetControlID="btn_lancer"
        ConfirmText="Are you sure you want to click this?"  önClientCancel="CancelClick" />--%>

Protected Sub btn_lancer_Click(ByVal sender As Object, ByVal e As EventArgs) Handles btn_lancer.Click
        'on recupere le nombre des inscris dans sesr et le nombre des inscris alertes
        Dim inscriptionDmp As New DataMapper_Cls_Inscription
        Dim numberInscris As Integer
        Dim numberInscrisAlerted As Integer
        numberInscris = inscriptionDmp.NumberConducteurAssignedToSesr(hf_idsesr.Value)
        numberInscrisAlerted = inscriptionDmp.NumberConducteurAssignedToSesrAndAlerted(hf_idsesr.Value)
        'on recupere le nombre minimum
        Dim paramDmp As New DataMapper_Cls_Parametre
        Dim numberMinInscris As Integer
        numberMinInscris = paramDmp.GetLastParameters().nombreMinInscrit
        'number Inscrits min est atteint
        If numberInscris >= numberMinInscris Then
            'tous les conducteurs sont alertes
            If numberInscris = numberInscrisAlerted Then
                Dim sesrDmp As New DataMapper_Cls_SESR
                sesrDmp.lanceeSesr(Convert.ToInt32(hf_idsesr.Value))
                Response.Redirect("~\Viewer\Gestionnaire\sesr\sesrGestionnaire.aspx")
            Else 'un conducteur au moins demeure inalerte
                hf_test.Value = "Nok"
                popPopupAlert.Show()
                PnlMsgAlert.Visible = True

            End If
        Else
            hf_test.Value = "wait"
            PnlMsg.Visible = True
            popPopup.Show()
        End If

    End Sub

    Private Sub btnOui_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnOui.Click
        'on recupere le nombre des inscris dans sesr et le nombre des inscris alertes
        Dim inscriptionDmp As New DataMapper_Cls_Inscription
        Dim numberInscris As Integer
        Dim numberInscrisAlerted As Integer
        numberInscris = inscriptionDmp.NumberConducteurAssignedToSesr(hf_idsesr.Value)
        numberInscrisAlerted = inscriptionDmp.NumberConducteurAssignedToSesrAndAlerted(hf_idsesr.Value)
        If numberInscris = numberInscrisAlerted Then
            Dim sesrDmp As New DataMapper_Cls_SESR
            sesrDmp.lanceeSesr(Convert.ToInt32(hf_idsesr.Value))
            Response.Redirect("~\Viewer\Gestionnaire\sesr\sesrGestionnaire.aspx")
        Else
            hf_test.Value = "nok2"
            popPopup.Hide()
            PnlMsgAlert.Visible = True
            popPopupAlert.Show()
        End If

    End Sub


    Private Sub btnNon_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnNon.Click
        popPopup.Hide()
    End Sub

    Private Sub btnAlertOK_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnAlertOK.Click
        'PnlMsgAlert.Visible = False
        popPopupAlert.Hide()
    End Sub