Your markup itself looks fine.
I'll try rewriting it for clarity's sake and ensure that all of your tags are properly closed :
<ContentTemplate><asp:Panel ID="pnlOptions" runat="server"><div id="tabs1" class="tabHeader"><input type="hidden" value='0' runat="server" id="ActiveTabIndex" /><ul class="scrollBottom"><li class='current'><a href="#abc">abc</a></li><li><a href="#def">def</a></li><li><a href="#ghi">ghi</a></li><li class='postback'><asp:LinkButton ID="tabjkl" EnableViewState="false" name="#jkl" runat="server" Text="jkl" OnClick="tabjkl_Click"></asp:LinkButton></li><li><a id="mno" runat="server" disabled="disabled" href="#mno">mno</a></li><li><a href="#pqr">pqr</a></li></ul></div></asp:Panel></ContentTemplate>
You might also try using the Developer Tools (F12) to see if any errors are present within the Console section.