我有两个嵌套的更新面板，我从源代码更新面板，但没有任何效果。代码如下
<div style="display:block; clear: left;" runat="server" id="DivLike">
<asp:UpdatePanel ID="UpdatePanelLike" runat="server" UpdateMode="Conditional">
<ContentTemplate>
<div style="position: relative;">
<div style="position: absolute; top: 0px; left: 0px;">
<asp:LinkButton ID="LinkButtonLike" runat="server" CommandName='<%#Eval("Like_Command") %>'
Font-Size="XX-Small" OnCommand="LinkButton2_Command" Text='<%#Eval("Like_Command")%>'></asp:LinkButton>
</div>
<div class="popupstyle" style="position:absolute; top:0px; left:0px; display:none;"
id="DivChapters" runat="server">
<asp:UpdatePanel ID="UpdatePanelLinkActivity" runat="server" UpdateMode="Conditional">
<ContentTemplate>
<div>Select Chapter:
<asp:DropDownList ID="DropDownListChapters" runat="server"
AutoPostBack="true" OnSelectedIndexChanged="DropDownListChapters_SelectedIndexChanged"></asp:DropDownList>
</div>
<div>Select Topic:
<asp:DropDownList ID="DropDownListTopics" runat="server"></asp:DropDownList>
</div>
<div>
<asp:LinkButton ID="LinkButtonAddLink" runat="server" OnCommand="LinkButtonAddLink_Command"
Text="Add" CssClass="UtilityClass"></asp:LinkButton>
</div>
<asp:UpdateProgress ID="UpdateProgressLinkActivity" runat="server" AssociatedUpdatePanelID="UpdatePanelLinkActivity"
DynamicLayout="True">
<ProgressTemplate>
<div style=" position:absolute; top:50%; left:50%; background-color:white;"
id="divLoading">
<img src="Images/loading25.gif" alt="Loading..." style="" />
</div>
</ProgressTemplate>
</asp:UpdateProgress>
</ContentTemplate>
<Triggers>
<asp:AsyncPostBackTrigger ControlID="LinkButtonAddLink" EventName="Command"
/>
</Triggers>
</asp:UpdatePanel>
</div>
</div>
</ContentTemplate>
<Triggers>
<asp:AsyncPostBackTrigger ControlID="LinkButtonLike" EventName="Command"
/>
</Triggers>
</asp:UpdatePanel>
</div>
下面的代码后面更新了面板，但没有更新任何面板。虽然当我用调试器分析它时，每一件事都被完美地分配了。
protected void DropDownListChapters_SelectedIndexChanged(object sender, EventArgs e )
{
DropDownList DDL = (DropDownList)sender;
DropDownListTopics.DataSource = ChapterDataAccess.GetUserTopics(Convert.ToInt32(DDL.SelectedItem.Value), new Guid(Membership.GetUser().ProviderUserKey.ToString()));
DropDownListTopics.DataTextField = "Name";
DropDownListTopics.DataValueField = "Id";
DropDownListTopics.DataBind();
ListItem item=new ListItem ("topics","value" );
DropDownListTopics.Items.Add(item);
UpdatePanel thepanel= (UpdatePanel)DDL.Parent.Parent;
UpdatePanel theparentpanel=(UpdatePanel)DDL.Parent.Parent.Parent.Parent.Parent ;
theparentpanel.Update();
thepanel.Update();
}