jQuery Grid Plugin - jqGrid

i am a newbie with php and im trying to use jquery grid, with the form edit, and delete.

I am implementing the edit ,it is appearing – error Status: 'error'. Error code: 0 ,when i press the submit

button ,the error apears but the changes are made… my grid…

<script>
var lastsel;
    $(function() {
        $("#toolbar").jqGrid({
            mtype: 'POST',
            editurl: 'http://www.onetag.pt/eulen/edi.....p&#39;, 
            caption:"Tags",
            colNames:['TagID','Nome', 'Descricao', 'Tipo'],
            colModel:[
            {name:'tagID',index:'tagID',hidden:true},
                {name:'name',index:'name',editable:true},
                {name:'description',index:'description',editable:true},
                {name:'type',index:'type'}
            ],
            datatype:"json
            height:421, 
            rownumWidth:40,
            pager:'#ptoolbar',
            rowList:[10,20,30],
            rowNum:10,
            sortname:'tagID',
            sortorder:'desc',
            url:'/tags/list/',
            viewrecords:true,
            width:740
        });
        $("#toolbar").jqGrid('navGrid','#ptoolbar',{del:true,add:false,edit:true,
search:true});
        $("#toolbar").jqGrid('filterToolbar',{stringResult:true,searchOnEnter:false});


    });
</script>

and the editurl.php

<?php

// connect to the database
$dbhost = "localhost";
$dbuser = "blah";
$dbpassword = "blah";
$database = "blah";
$tablename = "tags";
$db = mysql_connect($dbhost, $dbuser, $dbpassword)
or die("Connection Error: " . mysql_error());

 mysql_select_db($database) or die("Error conecting to db.");
//mysql_set_charset('utf8',$database);
mysql_query("SET NAMES 'utf8'");


 if($_POST['oper']=='add')
 {

 }
 if($_POST['oper']=='edit')
  {
$id     =   mysql_real_escape_string($_POST['id']);
$name     =   mysql_real_escape_string($_POST['name']);
$description   =   mysql_real_escape_string($_POST['description']);


$sql = "UPDATE ".$tablename." SET name ='".$name."', description ='".$description."' WHERE 
tagID = ".$id;

 $result=mysql_query($sql) or die(mysql_error());

 mysql_close($db);


 }
 if($_POST['oper']=='del')
 {

 } 
?>  

i select the first row,

and press edit button

then it appears the edit form…

then ive put the desired changes…

then press the submit button and the error appears…

i close the edit form, and press f5 to refresh, and the datafields have changed…

what can it be, in the edit.php, i have put a echo json_encode("end"); , because i was trying to see if the problem was the missing json reponse, but the error appears the same…

help….

Thanks in advance

Hugo Silva