Loading data into a cell of a table via AJAX

Guys,

I'm evaluating DataTables for a project I'm working on and have made excellent progress in the last day or so. I've loading large database tables into the DataTables object using AJAX and it's working beautifully.

However, one column of the table needs to come from another computed table lookup. So I need to load a cell with this data using an AJAX lookup. I tried doing this using the fnRender

"fnRender": function ( o, val ) {
jQuery.ajaxSetup ({ cache: false });
var row = $(this).closest('tr');
$(row).load('dt_getactivity.php');
}

but this doesn't work.

Can you guys shed some light on how to dynamically load this content?

Thanks in advance,

Tony