The first thing you should do is
validate your code. I notice a few errors in it which could be causing UDM not to work. Secondly, you have some javascripts that may be interfering with UDM's functionality. Try removing the embedded javascripts that are between the </style> and </head> tags. Also, comment out (for now anyway) your horizontal navigation menu at the bottom of the page, since that uses the javascripts you are removing above. See if UDM will work without all that stuff.