为啥我的tree不出来

<%@ page contentType="text/html; charset=gb2312" language="java" import="java.sql.*" errorPage="" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>服务平台</title>
<script src="jquery-1.4.2.js" language="javascript" type="text/javascript"></script>
<script src="jquery.ztree-2.6.js" language="javascript" type="text/javascript"></script>
<link href="demo/zTreeStyle/zTreeStyle.css" rel="stylesheet" type="text/css"/>
</head><body>
<script>
alert("1zenme mei you tree?")
var setting = {
    showLine: true,
    checkable: true
};
var zTreeNodes = [
    { "name":"google", "url":"http://g.cn", "target":"_blank"},
    { "name":"baidu", "url":"http://baidu.com", "target":"_blank"},
    { "name":"sina", "url":"http://www.sina.com.cn", "target":"_blank"}
];
//<ul id="tree" class="tree" style="width:300px; overflow:auto;"></ul>
var zTree = $("#tree").zTree(setting, zTreeNodes);
//var zTree;
$(function() {
zTree = $("#tree").zTree(setting, zTreeNodes);
 });</script>
</body>
</html>文件以temp.html存储，打开并不见tree,求教各位了????