DataTables

I'm hoping this is just a case of me overlooking the obvious, but I'd like to suppress the up/down arrows which appear in the headers of sortable columns when JQuery UI support is enabled.

I've got the following code, but it seems to have no effect (other lines removed for clarity):

       $.extend($.fn.dataTableExt.oJUIClasses, {
                    "sSortable": ''
                });

                $('#txnTable').dataTable({
                    "bJQueryUI": true
                });

Any help would be appreciated?

Thanks

Mark