jQuery Grid Plugin - jqGrid

I'm trying to create a simple table using JSON mapping and a java servlet. I'm new to jquery and web programming in general. Please help:

  <table id="jsonmap"></table>
  <div id="pjmap"></div>
  <script type="text/javascript">
   jQuery("#jsonmap").jqGrid({ url:'getdata', datatype: "json",
       colNames:['Inv No','Date', 'Client', 'Amount','Tax','Total','Notes'],
       colModel:[ {name:'id',index:'id', width:55},
       {name:'invdate',index:'invdate', width:90, jsonmap:"invdate"},
       {name:'name',index:'name asc, invdate', width:100},
       {name:'amount',index:'amount', width:80, align:"right"},
       {name:'tax',index:'tax', width:80, align:"right"},
       {name:'total',index:'total', width:80,align:"right"},
       {name:'note',index:'note', width:150, sortable:false} ],
       rowNum:10, rowList:[10,20,30], pager: '#pjmap', sortname: 'id', viewrecords: true,
       sortorder: "desc", jsonReader: { repeatitems : false, id: "0" },
       caption: "JSON Mapping", height: '100%' });

    jQuery("#jsonmap").jqGrid('navGrid','#pjmap',{edit:false,add:false,del:false});
   </script>

My servlet returns so far the following data:

{"jsonmap":[{"id":1, "invdate":"Fri Oct 15 12:31:22 EEST 2010", "name":"name", "amount":"1", "tax":"2"

, "total":"22", "note":"note"}]}

The data is not loading. Please help me.

Thank you,
Alex