jQuery Grid Plugin - jqGrid

Hi, can i ask some help in cell editing,why is it after i press F5 or refresh the jqgrid table,the records will turns to zero exept the one that i edited...here is my code

[CODE]

  <script type="text/javascript">

          $(function(){

            jQuery("#mygrid").jqGrid({
                url:'loaddata.php?param='+p1+'&param2='+p2,

                datatype: 'json',

               colNames:['STDID','NAME','DEPT','YEAR','ADDRESS','AGE'],

              colModel:[

                      {name:'std_id',index:'std_id',width:50,sortable:true},
                    {name:'firstname',index:'firstname',width:100,sortable:true},
                    {name:'dept',index:'dept',width:100,sortable:true,editable:true},
                    {name:'year',index:'year',width:100,sortable:true,editable:true},

                   {name:'address',index:'address',width:100,sortable:true,editable:true},

                   {name:'age',index:'age',width:100,sortable:true,editable:true}

             ],

               rowNum:10,
                rowList:[10,20,30],
                pager: '#pager2',
                sortname: 'std_id',
                viewrecords: true,
                sortorder: "desc",
                rowid:'std_id',
                cellEdit: true,
                id: 'std_id',
                caption:"Student Info",
                cellsubmit: 'remote',
                cellurl: 'update.php'

      });

     jQuery("#mygrid").jqGrid('navGrid','#pager2',{edit:false,add:false,del:false,search:false,refresh:false});

</script>

[/CODE]

please help me

Thank you in advance