Sortable: tables and Firefox

Hello!
I 've trying to figure how to work with tables and sortable objects.
The code above works well at IE, but in Firefox i cant make it work...
Does anyone know any kind od restrictions between FF and Scriptaculous?

<html>
<head>
<script type="text/javascript" src="../../javascript/prototype.js"
/></script>
<script type="text/javascript"
src="../../javascript/scriptaculous.js"></script>

</head>
<BODY>
<table border=1 style="position:relative;" >
  <tr id="linha">
    <td id="0">Nome</td>
    <td class="1" style='cursor: move;' id="1">Campo 1</td>
    <td class="1" style='cursor: move;' id="2">Campo 2</td>
    <td class="1" style='cursor: move;' id="3">Campo 3</td>
    <td class="1" style='cursor: move;' id="4">Campo 4</td>
  </tr>
  <tr align="center" id="linha3">
    <td>Nome simples</td>
    <td>1</td>
    <td>2</td>
    <td>3</td>
    <td>4</td>
  </tr>
  <tr align="center" id="linha4">
    <td>Nome simples</td>
    <td>1</td>
    <td>2</td>
    <td>3</td>
    <td>4</td>
  </tr>
</table>

<script type="text/javascript">
// <![CDATA[
    Sortable.create('linha',{tag:'td',dropOnEmpty:true,ghosting:true,
constraint:false,only:'1'});
// ]]>
</script>

</BODY>
</html>