Flexigrid - Lightweight but rich data grid

[eluser]eRic.Net[/eluser]
flexigrid is great!!
I'm using flexigrid in asp.net,but it doesn't work.

Response Content:

Code:

{page :1,total:2,rows:[{id:'1',cell:[{'1','Map_A','M',''}]},{id:'2',cell:[{'2','Map_B','N',''}]}]}

Code:

$(document).ready(function()
   {
        
        $("#GridBox").flexigrid(
        {
           url: 'ListMap.aspx',
            dataType: 'json',
            colModel : [
                {display: 'MapID', name : 'MapId', width : 100, sortable : true, align: 'center'},
                {display: 'Name', name : 'Name', width : 180, sortable : true, align: 'left'},
                {display: 'Shortcut', name : 'Shortcut', width : 220, sortable : true, align: 'left'},
                {display: 'Description', name : 'Description', width : 220, sortable : true, align: 'left'}
                ],
            buttons : [
                {name: 'Add', bclass: 'add'},
                {name: 'Delete', bclass: 'delete'},
                {separator: true}
                ],
            searchitems : [
                {display: 'Shortcut', name : 'Shortcut'},
                {display: 'Name', name : 'name', isdefault: true}
                ],
            sortname: "MapID",
            sortorder: "asc",
            usepager: true,
            title: 'Countries',
            useRp: true,
            rp: 15,
            showTableToggleBtn: true,
            width: 700,
            height: 200
    }
        );
   })

ListMap.aspx:

Code:

string JSON = "";
    protected void Page_Load(object sender, EventArgs e)
    {
        WWFansWebs webs = new WWFansWebs();
        JSON = webs.ListWwMap();
        Response.ContentType = "text/x-json";
        Response.Write(JSON);
        Response.End();
    }

where's wrong?