I've changed mi code:
<script> // perform JavaScript after the document is scriptable. $(function() { // setup ul.tabs to work as tabs for each div directly under div.panes $("ul.tabs").tabs("div.panes > div"); }); </script>
by this one:
<script> // perform JavaScript after the document is scriptable. jQuery(function() { // setup ul.tabs to work as tabs for each div directly under div.panes jQuery("ul.tabs").tabs("div.panes > div"); }); </script>
and now the tabs work fine.