Tabs controls are not displayed correctly

I have copied the following sample code from http://ajayagrahari.blogspot.com/2013/01/ajax-tabcontainer-examplesample-in.html
but it does not display tabs as it shows in the sample output on this site.  What am I doing wrong?
<%@ Page Title="" Language="C#" MasterPageFile="~/Site.Master" AutoEventWireup="true" CodeBehind="WebForm1.aspx.cs" Inherits="MyWebSite.WebForm1" %> <%@ Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit" TagPrefix="ajaxToolkit" %> <%@ Register Namespace="AjaxControlToolkit" Assembly="AjaxControlToolkit" tagPrefix="ajax" %> <asp:Content ID="Content1" ContentPlaceHolderID="HeadContent" runat="server"> <script type="t ...