you both the original jquery reference and the web assist jquery reference.
change:
<link type="text/css" href="webassist/forms/fd_sharp_default/Datepicker/css/jquery-custom.css" rel="stylesheet">
<script type="text/javascript" src="webassist/jquery/jquery-ui.js"></script>
to:
<link type="text/css" href="webassist/forms/fd_sharp_default/Datepicker/css/jquery-custom.css" rel="stylesheet">
<script type="text/javascript" src="webassist/jquery/jquery.js"></script>
<script type="text/javascript" src="webassist/jquery/jquery-ui.js"></script>