Tablesorter problem

Tablesorter problem

Hi, I´m trying to create from a table sortable table from this web http://tablesorter.com/docs/

<html>
<head>
<title>php stranka</title>
<script type="text/javascript" src="js/jquery.js"></script>
<script type="text/javascript" src="js/jquery.tablesorter.js"></script>
<script type="text/javascript">
       $(document).ready(function(){
           $("#myTable").tablesorter();
      });
</script>
</head>
<body>
<table id='myTable' ><thead><tr><th>ID</th><th>jmeno</th><th>prijemni</th></tr></thead><tbody><tr><td>1</td><td>roman</td><td>pokorny</td></tr><tr><td>2</td><td>ondra </td><td>pokorny</td></tr><tr><td>3</td><td>david</td><td>mrnka</td></tr></tbody></table></body>
</html>


but this code isnt working...

can you see any problem here ?