Hi on this page http://bit.ly/d67oe4 I would like the 'Top' button just above the footer to scroll the page back to the top using jquery. I am using the script below in the <head> of the page but the effect isn't working. Any idea why?

Code:
    <!-- Back to Top -->
    <script type="text/javascript">
    jQuery('a.backtotop').click(function(){
        alert('hello');
        jQuery('html, body').animate({scrollTop:0}, 'fast');
        return false;
    });
      </script>