jQuery Grid Plugin - jqGrid

i copy the the demo from the file,but  when i use the firfox5 it can not display the date except a word "undefine"! but when i use the chrome and safari , it can dispaly well !

may be you can say the order of js is important ,yes i use the stands orders of js ,but  it really display the data 。the following code for  this:

<link rel="stylesheet" href="main.css" type="text/css" /> 

<link rel="stylesheet" type="text/css" media="screen" href="css/ui-lightness/jquery-ui-1.8.2.custom.css" />

<link rel="stylesheet" type="text/css" media="screen" href="css/ui.jqgrid.css" />

<script src="js/jquery-1.5.2.min.js" type="text/javascript"></script>

<script src="js/i18n/grid.locale-en.js" type="text/jscript"></script>

<script src="js/jquery.jqGrid.min.js" type="text/javascript"></script>

<script src="js/jquery-ui-1.8.2.custom.min.js" type="text/javascript">

</script>

var mydata = [

{id:"1",invdate:"2010-05-24",name:"test",amount:"25",tax:"10.00",total:"2111.00",note:"note"} ];

jQuery("#list").jqGrid({

data: mydata,

datatype: "local",

height: 150,

rowNum: 10,

rowList: [10,20,30],

colNames:['Inv No','Date', 'Client', 'Amount','Tax','Total','Notes'],

colModel:[

{name:'id',index:'id', width:60, sorttype:"int"},

{name:'invdate',index:'invdate', width:90, sorttype:"date", formatter:"date"},

{name:'name',index:'name', width:100},

{name:'amount',index:'amount', width:80, align:"right",sorttype:"float", formatter:"number"},

{name:'tax',index:'tax', width:80, align:"right",sorttype:"float"},

{name:'total',index:'total', width:80,align:"right",sorttype:"float"},

{name:'note',index:'note', width:150, sortable:false}

],

pager: "#plist",

viewrecords: true,

caption: "Manipulating Array Data"

});

</script>

the result:

sorry ! it can not insert the local picture !

hope you answer ! thanks~