CollapsiblePanelExtender and Repeater within a repeater

Hi guys

Really struggling and can't seem to get my collapsible panel to work. I have a repeater within a repeater. I want to collapse the data in the second repeater and only display when i click on an item in the first repeater. Can't figure out where I'm going wrong...

The data in both repeaters is returning as expected..the only thing I'm stuck with now is the collapsing panels...any help appreciated!

<asp:Repeater ID="rptTier" runat="server" DataSourceID="SqlDataSource1" EnableViewState="true"><HeaderTemplate><table><tr><td colspan="4" align="center"></td></tr><tr><td width="100"><font size="4" color="black">Broker</font></td><td width="100"><font size="4" color="black">Votes</font></td><td width="100"><font size="4" color="black">$ Value</font></td><td width="100"></td><td><font size="4" color="black">Comment</font></td>   </tr> </HeaderTemplate><ItemTemplate><tr><td><asp:panel ID="pnlTier" runat="server"><b><asp:Label ID="lblTier" runat="server"></asp:Label></b><asp:ImageButton ID="Image1" runat="server" ImageUrl="~/Images/Expand.png" AlternateText="(Show Details...)"/></asp:panel></td></tr><asp:CollapsiblePanelExtender ID="cpeDesc" runat="Server"
        TargetControlID="pnlBroker"
        ExpandControlID="pnlTier"
        CollapseControlID="pnlTier"
        Collapsed="True"
        ExpandedImage="~/Images/Collapse.png"
        CollapsedImage="~/Images/Expand.png"
        ImageControlID="Image1"
         /> <asp:Panel ID="pnlBroker" runat="server" ><asp:repeater ID="rptBroker" runat="server" OnItemDataBound="rptBroker_ItemDataBound" ViewStateMode="Enabled"><ItemTemplate><tr><td><asp:Label ID="lblBroker" runat="server"></asp:Label></td><td><asp:TextBox Rows="1" Columns="3" ID="txtVote" runat="server" OnTextChanged="txtVoteChanged" AutoPostBack="true"></asp:TextBox></td><td><asp:Label id="lblexec" runat="server" Visible="false"></asp:Label>&nbsp;<asp:Label ID="lblresearch" runat="server" Visible="false"></asp:Label>&nbsp;$<asp:label ID="lblExpComm" runat="server"></asp:label></td><td></td><td><asp:textbox TextMode="MultiLine" ID="txtComment" runat="server" Rows="3" columns="40">Insert broker comment here.</asp:textbox> </td>   </tr></ItemTemplate></asp:repeater></asp:Panel></ItemTemplate><FooterTemplate></table></FooterTemplate></asp:Repeater></div>