Ignore me!

I've linked up my question with this post - http://www.trirand.com/blog/?p.....undefined/ . But getting a little impatient and worried that people might not look at older posts.  Can you please tell me what's wrong with this json and this jsonreader? For some reason i'm not able to populate the grid with actual data although i have the correct number of rows.

my json looks like this and is a valid json

{
    "records": 4,
    "total": 5,
    "rows": [
        {
            "cell": {
                "lastname": "V",
                "_type": "User",
                "uid": "u11",
                "firstname": "Megha"
            }
        },
        {
            "cell": {
                "lastname": "V",
                "_type": "User",
                "uid": "u12",
                "firstname": "Prashant"
            }
        },
        {
            "cell": {
                "lastname": "A",
                "_type": "User",
                "uid": "u1",
                "firstname": "Shalini"
            }
        },
        {
            "cell": {
                "lastname": "V",
                "_type": "User",
                "uid": "u0",
                "firstname": "Megha"
            }
        }
    ]
}

This is my grid description -

$(document).ready(function(){
// This is a basic jqGrid with a navGrid (that adds a search button)
    jQuery('#list').jqGrid({
        url:'/user/get_users/',
        datatype: "json",
        
    colNames: ['First Name','Last Name','UID'],
        colModel: [{
                name: 'firstname',
                index: 'firstname'
            }, {
                name: 'lastname',
                index: 'lastname'
            }, {
                name: 'uid',
                index: 'uid asc, invdate'
            }],
    jsonReader : {
             root: "rows",
             page: "page",
             total: "total",
             records: "records",  
             repeatitems: false,
             cell: "cell",
             id: "id",
             userdata: "userdata",    
       },
        rowNum:10,
        rowList:[10,20,30],
        multiselect: false,
        width: 700,
        height: 100,
        pager: jQuery('#pager'),
        sortname: 'uid',
        viewrecords: true,
        sortorder: "asc",
        caption: "Users"
    }).navGrid("#pager",{edit:false,add:false,del:false},{},{width:200},{});
});