C# 在UpdatePanel中找不到该触发器的ID为的控件

我正在编写一个ASP.NET代码，用于根据性别更改最低结婚年龄

 <asp:Accordion ID="accSearchCategory" HeaderCssClass="accordionHeader"
                    HeaderSelectedCssClass="accordionHeaderSelected"
                    ContentCssClass="accordionContent" runat="server" SelectedIndex="0" FadeTransitions="true"
                    SuppressHeaderPostbacks="true" TransitionDuration="250" FramesPerSecond="40"
                    RequireOpenedPane="false" AutoSize="None">
    <Panes>
        <asp:AccordionPane ID="accPanSex" runat="server">
            <Header>
                Sex
            </Header>
            <Content>
                <asp:UpdatePanel ID="updPanelSex" UpdateMode="Conditional" runat="server" >
                    <ContentTemplate>
                        <asp:DropDownList ID="ddlSex" runat="server" OnSelectedIndexChanged="ddlSex_SelectedIndexChanged" AutoPostBack="true">
                            <asp:ListItem Text="Male" Value="0"></asp:ListItem>
                            <asp:ListItem Text="Female" Value="1"></asp:ListItem>
                        </asp:DropDownList>
                    </ContentTemplate>
                </asp:UpdatePanel>
            </Content>
        </asp:AccordionPane>
        <asp:AccordionPane ID="accPanMaritalStatus" runat="server">
            <Header>
                Marital Status
            </Header>
            <Content>
                <asp:UpdatePanel ID="updPanelMaritalStatus" UpdateMode="Conditional" runat="server">
                    <ContentTemplate>
                        <asp:DropDownList ID="ddlMaritalStatus" runat="server">
                            <asp:ListItem Text="Single" Value="0"></asp:ListItem>
                            <asp:ListItem Text="Divorced" Value="1"></asp:ListItem>
                            <asp:ListItem Text="Separated" Value="2"></asp:ListItem>
                            <asp:ListItem Text="Widowed" Value="3"></asp:ListItem>
                        </asp:DropDownList>
                    </ContentTemplate>
                    <Triggers></Triggers>
                </asp:UpdatePanel>
            </Content>
        </asp:AccordionPane>
        <asp:AccordionPane ID="accPanAge" runat="server">
            <Header>
                Age
            </Header>
            <Content>
                <table>
                    <tr>
                        <td>From&nbsp;
                        </td>
                        <td>
                            <asp:UpdatePanel ID="updPanelFromAge" UpdateMode="Conditional" runat="server" ChildrenAsTriggers="false">
                                <ContentTemplate>
                                    <asp:TextBox ID="txtFromAge" runat="server" OnTextChanged="txtFromAge_TextChanged" AutoPostBack="true"></asp:TextBox>
                                    <asp:SliderExtender ID="txtFromAge_SliderExtender" runat="server" Maximum="49" Minimum="18"
                                        BoundControlID="txtShowFromAge" TargetControlID="txtFromAge">
                                    </asp:SliderExtender>
                                </ContentTemplate>
                                <Triggers>
                                    <asp:AsyncPostBackTrigger ControlID="ddlSex" EventName="SelectedIndexChanged" />
                                </Triggers>
                            </asp:UpdatePanel>
                        </td>
                        <td>&nbsp;</td>
                        <td>
                            <asp:UpdatePanel ID="updPanelShowFromAge" UpdateMode="Conditional" runat="server">
                                <ContentTemplate>
                                    <asp:TextBox ID="txtShowFromAge" runat="server" CssClass="form-text inline" Width="50px"
                                        ></asp:TextBox>
                                </ContentTemplate>
                                <Triggers>
                                    <asp:AsyncPostBackTrigger ControlID="ddlSex" EventName="SelectedIndexChanged" />
                                </Triggers>
                            </asp:UpdatePanel>
                        </td>
                    </tr>
                    <tr>
                        <td>To&nbsp;
                        </td>
                        <td>
                            <asp:UpdatePanel ID="updPanelToAge" UpdateMode="Conditional" runat="server">
                                <ContentTemplate>
                                    <asp:TextBox ID="txtToAge" runat="server"></asp:TextBox>
                                    <asp:SliderExtender ID="txtToAge_SliderExtender" runat="server" Maximum="50" Minimum="19"
                                        BoundControlID="txtShowToAge" TargetControlID="txtToAge">
                                    </asp:SliderExtender>
                                     </ContentTemplate>
                                <Triggers>
                                    <asp:AsyncPostBackTrigger ControlID="txtFromAge" EventName="TextChanged" />
                                </Triggers>
                            </asp:UpdatePanel>
                                    </td>
                        <td>&nbsp;</td>
                                    <td>
                                        <asp:UpdatePanel ID="updPanelShowToAge" UpdateMode="Conditional" runat="server">
                                <ContentTemplate>
                                        <asp:TextBox ID="txtShowToAge" runat="server" CssClass="form-text inline" Width="50px"></asp:TextBox>
                                    &nbsp;years
                                </ContentTemplate>
                                <Triggers>
                                    <asp:AsyncPostBackTrigger ControlID="txtFromAge" EventName="TextChanged" />
                                </Triggers>
                            </asp:UpdatePanel>
                        </td>
                    </tr>
                </table>
            </Content>
        </asp:AccordionPane>
        <asp:AccordionPane ID="accPanLocatedIn" runat="server">
            <Header>
                Located in
            </Header>
            <Content>
                <asp:UpdatePanel ID="updPanelLocation" UpdateMode="Conditional" runat="server">
                    <ContentTemplate>
                        <asp:DropDownList ID="ddlBirthState" runat="server"
                        </asp:DropDownList>
                    </ContentTemplate>
                    <Triggers></Triggers>
                </asp:UpdatePanel>
            </Content>
        </asp:AccordionPane>
    </Panes>
</asp:Accordion>

我知道这是一个可访问性问题，但似乎没有任何效果。
我认为您应该在使用triger的updatepanel中使用id为ddlSex的控件，这将彻底改变我的设计。还有其他方法吗。尝试将所有内容包装在一个UpdatePanelId中，但现在我得到了与txtFromAge相同的错误