jQuery Grid Plugin - jqGrid

I'm using jqGird version : "4.4.0". However, the client side sorting does not work. This is the grid definition:

$(function() {

$("#fileGrid").jqGrid(

{ multiselect:true,

datatype : 'json',

mtype : 'get',

colNames : [ 'FileID', 'File Name', 'Group Name', 'Date Created', 'Date Uploaded', "Upload URL", "Upload Session" ],

colModel : [ {

name : 'id',

jsonmap : 'id',

width : 5,

align : 'center',

hidden:false,

key:true

},{

name : 'fileName',

jsonmap : 'fileName',

width : 30,

align : 'left'

}, {

name : 'groupName',

jsonmap : 'groupName',

width : 10,

align : 'left'

}, {

name : 'createdDT',

jsonmap : 'createdDT',

width : 10,

align : 'left'

}, {

name : 'uploadedDT',

jsonmap : 'uploadedDT',

width : 10,

align : 'left'

}, {

name : 'uploadURL',

jsonmap : 'uploadURL',

width : 10,

align : 'left'

}, {

name : 'uploadSessionID',

jsonmap : 'uploadSessionID',

width : 10,

align : 'left'

}

],

autowidth : true,

viewrecords : true,

gridview : true,

rowNum : -1,

jsonReader : {

repeatitems : false,

root : "rows",

page : "currPage",

total : "totalPages",

records : "totalRecords"

}

//onCellSelect : onCellSelect

});

});

This is how the grid is populated:

function updateFileGrid(result) {

alert("updateFileGrid.result=" + JSON.stringify(result));

/*for (myvar in result) {

alert("updateFileGrid.result.myvar=" + myvar);

}*/

//fileGridData = result;

$("#fileGrid")[0].addJSONData(result);

$("#fileGrid").setGridParam({datatype:'local'});

}

The data displayed by the alert dialog is

updateFileGrid.result={

"currPage":1,

"rows":[{"createdDT":"9/6/12 3:20 PM","fileName":"FnAAAA","groupName":"GrpAAAA","id":"100","uploadSessionID":null,"uploadURL":null,"uploadedDT":null},

{"createdDT":"9/6/12 4:20 PM","fileName":"FnBBBB","groupName":"GrpBBBB","id":"200","uploadSessionID":null,"uploadURL":null,"uploadedDT":null},

{"createdDT":"9/6/12 5:20 PM","fileName":"FnCCCC","groupName":"GrpCCCC","id":"300","uploadSessionID":null,"uploadURL":null,"uploadedDT":null}],

"totalPages":1,

"totalRecords":3}

I need to sort the data on the client side. However, the local (client side) sorting does not work at all. I played around with datatype : 'local', which resulted the data disappear. I added the event handler loadComplete to change the datatype to local, but it is never called.

How can I achieve local sorting of the data when the grid is populated via addJSONData, and there is no url for the the grid?

Your help is appreciated.