ASP.NET Panel Not Ending - asp.net

Question

I have created an ASP.NET page with an AJAX Accordion control. Within on the panes are several controls, some of which I've placed inside a Panel control, for various reasons.
However, controls which are on the page AFTER the closing tag for the panel are appearing INSIDE the panel when the page is rendered. For the life me I can't figure out why, and it's driving me crazy! Even clicking on the header of the Accordion Pane after the one containing the panel doesn't cause the Pane to expand, which it did before I added the Panel, seemingly because even IT is behaving as if it's within the Panel!
Any ideas what I'm doing wrong? How can I make the page believe that the panel ends!!?
<asp:Accordion ID="accQuestionnaire" runat="server" RequireOpenedPane="false" ContentCssClass="AccordionContent" HeaderCssClass="AccordionHeader" FadeTransitions="true"
transitionduration="250" HeaderSelectedCssClass="AccordionSelected" SelectedIndex="0" SuppressHeaderPostbacks="true" >
<Panes>
<%--START OF Tristan Link Pane (0)-------------------------------------------------------------%>
<asp:AccordionPane ID="pnTristanLink" runat="server" ContentCssClass="AccordionContent" ViewStateMode="Enabled" >
<Header>
Tristan Link
</Header>
<Content>
<div class="centrebuttonsdiv" >
<asp:Button ID="btnSearchTristan" runat="server" CssClass="largebutton" Text="Search Tristan" /><br />
</div>
<asp:Panel ID="pnlTristanSearch" runat="server" CssClass="panel" >
<div class="leftdiv"> <%--Matching Tristan results--%>
<asp:FormView ID="fvTristanSearch" runat="server" CssClass="FormView" >
<ItemTemplate>
<asp:Label ID="lblTristanSearchLabel" runat="server" CssClass="fieldtitle" Text="The information from Tristan for this Case Number is:" /><br /><br />
<asp:Label ID="lblAnimalNameLabel" runat="server" CssClass="fieldtitle" Text="Horse Name: " />
<asp:Label ID="lblAnimalName" runat="server" Text='<%# Eval("PetName") & " " & Eval("ClientNameLast") %>' /><br />
<asp:Label ID="lblGenderLabel" runat="server" CssClass="fieldtitle" Text="Sex: " />
<asp:Label ID="lblGender" runat="server" Text='<%# Eval("L_GenderDesc") %>' /><br />
<asp:Label ID="lblBreedLabel" runat="server" CssClass="fieldtitle" Text="Breed: " />
<asp:Label ID="lblBreed" runat="server" Text='<%# Eval("L_BreedDesc") %>' /><br />
<asp:Label ID="lblDOBLabel" runat="server" CssClass="fieldtitle" Text="DOB: " />
<asp:Label ID="lblDOB" runat="server" Text='<%# Eval("PetDOB", "{0:d}") %>' /><br /><br />
</ItemTemplate>
</asp:FormView>
</div>
<div class="rightdiv">
<br /><br />
<asp:Label ID="lblUnmatchedAppointments" runat="server" Text="Appointments for this horse with no Colic Study details:" Visible="false" /><br />
<asp:ListBox ID="lstUnmatchedAppointments" runat="server" DataSourceID="SQLUnmatchedAppointments" DataTextField="AppointmentDate" DataTextFormatString="{0:d}" DataValueField="AppointmentID"
Visible = "False" />
</div>
<div class="cleardiv" />
</asp:Panel>
<div class="centrebuttonsdiv" >
<asp:Label ID="lblTristanSearchInstructions" runat="server" Text="Select an appointment from the list above and click 'Save Section' to continue. Otherwise, click 'Clear Retrieved Information'
to search again" Visible="false" /><br />
<asp:Button ID="btnClearTristanSearch" runat="server" Text="Clear Retrieved Information" Visible="false" CssClass="largebutton" />
<asp:Button ID="btnSaveTristanLink" runat="server" Text="Save Section" OnClientClick="disablePanes()" Visible="false" Enabled="false" CssClass="largebutton" />
</div>
</Content>
</asp:AccordionPane>

Answer 1

I believe that changing this line:
<div class="cleardiv" />
to this
<div class="cleardiv"></div>
will solve that rendering problem; <div> is not typically a self-closing tag.