extjs4.1版本 树形菜单问题
<link type="text/css" href="ext-all.css" rel="stylesheet"/>
<script language="javascript" src="Ext.Base.js"></script>
<script language="javascript" src="ext-all.js"></script>
<script>
Ext.onReady(function(){
var root=new Ext.tree.TreeNode({
id:"root",
text:"根节点"
});
var tree=new Ext.tree.TreePanel({
renderTo:"tree",
root:root,
width:200
});
});
</script>
</head>
<body>
<div id="hello"></div>
<div id="tree"></div>
</body>
</html>
该导的包也导了，可运行的时候，var root=new Ext.tree.TreeNode老是报缺少对象，或者Ext未定义等问题。。。敢问各路大侠是哪儿的问题？
[解决办法]
