UpdatePanel Not Refreshing In Accordion?

I'm using MS AJAX's accordion control. It works fine normally, but I can't seem to get it to work with an UpdatePanel. My layout is like this:

<div id="accordion">
<div><a href="#">Header1</a></div>
<div class="acc_content">
<asp:UpdatePanel ID="UpdatePanel1" runat="server" UpdateMode="Conditional" >
<ContentTemplate>
<asp:button id="btnToggle" runat="server" text="toggle"/>
//my repeater contents go here. The buttons within the repeater cause a postback, but changes cannot be seen unless the page is manually refreshed (since the updatepanel doesn't refresh)
</ContentTemplate>
<Triggers>
<asp:AsyncPostBackTrigger ControlID="btnToggle" EventName="click" />
<asp:AsyncPostBackTrigger ControlID="btnAdd" EventName="click" /> //this button is outside the updatepanel
</ContentTemplate>
</Triggers>
</asp:UpdatePanel>
</div>
<div><a href="#">Header 2 </a></div>
<div class="acc_content">
Content of the second pane
</div>
</div>

There are postbacks occurring when I click the buttons, but the updatepanel never refreshes or updated. I tried adding UpdatePanel1.Update() in the code-behind for each postback event, but no luck. Any ideas as to why this is happening?