[jQuery] Draggable() doesn't work with table rows?

[René]

I can drag and sort lists.
I can sort tables.
I can drag entire tables.

But I can't drag individual table rows. Anyone know how to do it?
Here's some sandbox code:

<ul id="list">
<li id="a_1" class="drag1">The</li>
<li id="a_2" class="drag1">slow</li>
<li id="a_3" class="drag1">green</li>
<li id="a_4" class="drag1">turtle</li>
</ul>

<table id="table">
<tbody id="rows">
<tr id="a_1" class="drag2"><td>The</td></tr>
<tr id="a_2" class="drag2"><td>quick</td></tr>
<tr id="a_3" class="drag2"><td>brown</td></tr>
<tr id="a_4" class="drag2"><td>fox</td></tr>
</tbody>
</table>

<script type="text/javascript" src="http://ajax.googleapis.com/ajax/
libs/jquery/1.2.6/jquery.min.js"></script>
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/
libs/jqueryui/1.5.2/jquery-ui.min.js"></script>
<script type="text/javascript">

$(document).ready(function() {
        $('.drag1').draggable();                // WORKS
//      $('#list').sortable();                  // WORKS
//      $('#rows').sortable();                  // WORKS
//      $('#table').draggable();                // WORKS
//      $('#rows').draggable();                 // DOESN'T WORK  -- ?
        $('.drag2').draggable();                // DOESN'T WORK  -- ?
//      $('#a_1').draggable();                  // DOESN'T WORK  -- ?
        });

</script>