jQuery Grid Plugin - jqGrid

Hi all,

I'm using 3.5.3 library version. I'm trying to use the cell edit option. I cannot able to save to DB in the cell edit mode, but it work fine if I click on the down-left grid corner and use the 'edit selected row' . In this case the data are saved to the DB . This is my celledit.js file:

jQuery("#celltbl").jqGrid({
    url:'server.php?q=2',
 datatype: "json",
        mtype: 'POST',
        cellsubmit: 'clientArray',
        cellEdit: true,
        cellurl: 'update.php',
        editurl: 'update.php',
    colNames:['Inv No','Date', 'Client', 'Amount','Tax','Total','Notes'],
    colModel:[
     {name:'id',index:'id', width:55},
     {name:'invdate',index:'invdate', width:90,editable:true},
     {name:'name',index:'name asc, invdate', width:100},
     {name:'amount',index:'amount', width:80, align:"right",editable:true,editrules:{number:true}},
     {name:'tax',index:'tax', width:80, align:"right",editable:true,editrules:{number:true}},  
     {name:'total',index:'total', width:80,align:"right"},  
     {name:'note',index:'note', width:150, sortable:false}  
    ],
    rowNum:10,
    rowList:[10,20,30],
    imgpath: gridimgpath,
    pager: jQuery('#pcelltbl'),
    sortname: 'id',
    viewrecords: true,
    sortorder: "asc",
    caption:"Cell Edit Example",
 forceFit : true,
 cellsubmit: 'clientArray',
 afterEditCell: function (id,name,val,iRow,iCol){
  if(name=='invdate') {
   jQuery("#"+iRow+"_invdate","#celltbl").datepicker({dateFormat:"yy-mm-dd"});
  }
 },
 afterSaveCell : function(rowid,name,val,iRow,iCol) {
  if(name == 'amount') {
   var taxval = jQuery("#celltbl").getCell(rowid,iCol+1);
   jQuery("#celltbl").setRowData(rowid,{total:parseFloat(val)+parseFloat(taxval)});
  }
  if(name == 'tax') {
   var amtval = jQuery("#celltbl").getCell(rowid,iCol-1);
   jQuery("#celltbl").setRowData(rowid,{total:parseFloat(val)+parseFloat(amtval)});
  }
 }
}).navGrid('#pgwidth',{edit:true,add:false,del:false});

Any help?