Update,search is not working in serverside using php

sabari

this is my code can any help plz
link rel="stylesheet" type="text/css" href="/datatable/css/demo_page.css" rel="stylesheet" type="text/css" />





$(document).ready( function () {
$('.dataTable').dataTable({
'bProcessing' : true,
'bServerSide' : true,
'sAjaxSource' : datatables.php',
'sPaginationType': 'full_numbers',
'bAutoWidth' : false,
"bJQueryUI": true,
'aoColumns' : [
{ 'sName': '1' },
{ 'sName': '2'},
{ 'sName': '3' },
{ 'sName': '4' },
{ 'sName': '5' }
],
'fnServerData' : function(sSource, aoData, fnCallback)
{
$.ajax({
'dataType': 'json',
'type' : 'POST',
'url' : sSource,
'data' : aoData,
'success' : fnCallback

});
},
});
} );


my PHP CONTENt is

<?php
echo '{
"sEcho": 1,
"iTotalRecords": 2,
"iTotalDisplayRecords": 2,

"aaData": [
{
"DT_RowId": "row_7",
"DT_RowClass": "gradeA",
"0": "Gecko",
"1": "Firefox 1.0",
"2": "Win 98+ / OSX.2+",
"3": "'.rand().'",
"4": "'.rand().'"
},
{
"DT_RowId": "row_8",
"DT_RowClass": "gradeA",
"0": "Gecko",
"1": "Firefox 1.5",
"2": "Win 98+ / OSX.2+",
"3": "'.rand().'",
"4": "'.rand().'"
}]}';


?>
while page loading it was working good. then i try to change page or sort the table .no operation is done plz can any one help me

thak you.