MessageBox won't prompt out

Hi all,

I have a master page. Inside master page i have doing a loading update panel, pleae see below code:

<asp:ToolkitScriptManager ID="ToolkitScriptManager1" runat="server">
</asp:ToolkitScriptManager>
                   <asp:UpdatePanel ID="UpdatePanel1" runat="server">
                    <ContentTemplate>
                        <asp:ContentPlaceHolder ID="ContentPlaceHolder1" runat="server">
                        </asp:ContentPlaceHolder>
                    </ContentTemplate>
                    <Triggers>
                        <asp:AsyncPostBackTrigger ControlID="Menu1"/>
                    </Triggers>
                    </asp:UpdatePanel>
                    <asp:UpdateProgress ID="UpdateProgress1" runat="server" DynamicLayout="false" DisplayAfter="0">
                    <ProgressTemplate>
                        <div id="overlay">
                            <div id="modalprogress">
                                <div  id="theprogress">
                                    <asp:Image ID="loader" runat="server" ImageAlign="AbsMiddle" ImageUrl="~/images/ajax-loader.gif" />
                                </div>
                            </div>
                        </div>
                    </ProgressTemplate>
                    </asp:UpdateProgress>
                    <asp:UpdatePanelAnimationExtender ID="UpdatePanelAnimationExtender1" runat="server" Enabled="True" TargetControlID="UpdatePanel1">
                    </asp:UpdatePanelAnimationExtender>

I create a another new page with one button. Inside the button i have put a message box, please see below for code infront and code behind:

                        <asp:UpdatePanel ID="UpdatePanel1" runat="server">
                        <ContentTemplate>
                        <asp:Button ID="btnSave" runat="server" BackColor="#EFF3FB"
                        onclick="btnSave_Click" style="font-family: 'Century Gothic'; height: 27px;"
                        Text="Save" />
                        </ContentTemplate>
                        <Triggers>
                            <asp:AsyncPostBackTrigger  ControlID = "btnSave" EventName = "Click"/>
                        </Triggers>
                        </asp:UpdatePanel>

    protected void btnSave_Click(object sender, EventArgs e)
    {

      Toolbox.MessageBox.Show("hi");

    }

The problem is when i click the button, it didnt show me the message?Anyone can help me?