How to reproduce it :

• in head.xsl comment lines 142 and 177 to 183 :

  <link rel="stylesheet" type="text/css" href="{ametys:skinURL('css/jqtransform.css')}" media="screen,print,handheld"/>

  	<script type="text/javascript" src="{ametys:skinURL('js/jquery.jqtransform.js')}"></script>
     				<script type="text/javascript">
     					$j(function() {
  					    //find all form with class jqtransform and apply the plugin
  					    $j(".ametys-cms-content, .ametys-cms-service").not(".no-jqtransform").find('form').jqTransform();
  					});
     				</script>

• add a link directory service in a page with all options checked
• in FO, try to add a favorite link
  > An error has occurred while adding favorite : Uncaught TypeError: $j(...).jqTransform is not a function

Laurence P. reproduce it with a skin without jqtransform