As far as I can diagnose the problem, you havent included the JQuery file... Please download it or use a CDN to get the JQuery file.
The head section should contain the following
script
tags.
<script src="http://ajax.aspnetcdn.com/ajax/jquery/jquery-1.5.1.min.js" type="text/javascript"></script>
<script type="text/javascript" src="js/BlockUI-2.42.js"></script>
If does not solve your problem, do let me know. I will update this solution and help you. Thanks.