problem sorting in FixedColumns

I all,

this is my simple code :

<script type="text/javascript" charset="utf-8">
$(document).ready( function () {
var oTable = $('#tabella5').dataTable( {
"sScrollX": "100%",
"sScrollXInner": "120%",
"bScrollCollapse": true
} );
new FixedColumns( oTable, {
"iLeftColumns": 2,
"iLeftWidth": 250
} );
} );
</script>

it sorting well when table not contains tags, for example like this :


<table>
<tr height="25px" class="gradeA">
<td align="left"><?php echo number_format($var1,2);?></td>
<td align="center"><?php echo number_format($var2,2);?></td>
.....
.....
</tr>
</table>

vars are percentuals.

but it don't sort columns when I add any HTML tags in TD tags like this :

<tr height="25px" class="gradeA">
<td align="left"><div class='cla'><a href='link'><?php echo number_format($var1,2);?></a></div></td>
<td align="center"><div class='cla'><a href='link'><?php echo number_format($var2,2);?></a></div></td>
.....
.....
</tr>
</table>


Can anyone tell me why ?

TNX ALL