UpdatePanel导致ASP.net中的整页回发

Question

我是ASP.NET的初学者，我遇到了UpdatePanel的问题：它导致整页回发而不是部分回发。这是我的代码：

<asp:Panel ID="BottomPanel" runat="server" BorderStyle="Ridge">
    <table>
        <tr>
            <td align="center">
                <br />
                <asp:ToolkitScriptManager ID="ToolkitScriptManager1" EnablePartialRendering="true"
                    runat="server">
                </asp:ToolkitScriptManager>
                <asp:CheckBoxList runat="server" ID="GroupCheckBoxList" RepeatColumns="10" RepeatDirection="Horizontal"
                    RepeatLayout="Table" AutoPostBack="true" ClientIDMode="AutoID" OnSelectedIndexChanged="GroupCheckBoxList_SelectedIndexChanged">
                </asp:CheckBoxList>
            </td>
        </tr>
        <tr>
            <td>
                <asp:UpdatePanel ID="GroupUpdatePanel" runat="server" Visible="true" UpdateMode="conditional">
                    <ContentTemplate>
                        <asp:Panel ID="GroupGraphPanel" runat="server" Visible="true">
                        </asp:Panel>
                    </ContentTemplate>
                    <Triggers>
                        <asp:AsyncPostBackTrigger ControlID="GroupCheckBoxList" EventName="SelectedIndexChanged" />
                    </Triggers>
                </asp:UpdatePanel>
            </td>
        </tr>
    </table>
</asp:Panel>

任何帮助将不胜感激！