jQuery Grid Plugin - jqGrid

Sorry my english is very pool.

when i try to use jqgrid with the JSON data, i get this picture:

i use a java servlet to provide the json data. and the data like this:

{"page":1,"records":4,"rows":[{"age":24,"id":0,"name":"talen"},{"age":24,"id":1,"name":"talen"},{"age":24,"id":2,"name":"talen"},{"age":24,"id":3,"name":"talen"}],"total":1}

and my sourcecode of the page is :

$(function() {
            jQuery("#jsonmap1").jqGrid({
                url:'jsonServlet',
                datatype: "json",
                colNames:['id','name', 'age'],
                colModel:[
                        {name:'id',index:'id', width:100},
                        {name:'name',index:'name', width:200},
                        {name:'age',index:'age', width:100}],
                rowNum:10,
                rowList:[10,20,30],
                sortname: 'id',
                viewrecords: true,
                pager: '#pjmap1',
                sortorder: "desc",
                jsonReader: { repeatitems : false},
                height: '100%'
            });

            jQuery("#jsonmap1").jqGrid('navGrid','#pjmap1',{edit:false,add:false,del:false});
        });

......

<table id="jsonmap1" class="scroll" cellpadding="0" cellspacing="0"></table>
    <div id="pjmap1" class="scroll" style="text-align:center;"></div>

what is wrong? please help me, thx