you conflicting versions of jquery on this page.
this line attaches jquery version 1.7 for the date picker:
<script type="text/javascript" src="webassist/forms/fd_sharp_default/Datepicker/js/jquery-ui-1.7.1.custom.min.js"></script>
further own the page, you attach version 1.6:
<script type="text/javascript" src="../ScriptLibrary/jquery-latest.pack.js"></script>
these two are clashing and causing the date picker to not work.