asp.net ext 2.0.2 tree 树型菜单,为啥显示不出来了??

left.aspx 代码
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" >
<HTML>
<HEAD>
<title>left</title>
<meta name="GENERATOR" Content="Microsoft Visual Studio .NET 7.1">
<meta name="CODE_LANGUAGE" Content="C#">
<meta name="vs_defaultClientScript" content="JavaScript">
<meta name="vs_targetSchema" content="http://schemas.microsoft.com/intellisense/ie5">
<link rel="stylesheet" type="text/css" href="../css/ext-all.css" />    <!-- GC -->
  <!-- LIBS -->
  <script type="text/javascript" src="../js/ext-base.js"></script>
  <!-- ENDLIBS -->    <script type="text/javascript" src="../js/ext-all.js"></script>
<script type="text/javascript" src="../js/reorder.js"></script><!-- Common Styles for the examples -->
<link rel="stylesheet" type="text/css" href="../css/examples.css" />
</HEAD>
<body MS_POSITIONING="GridLayout">
<form id="Form1" method="post" runat="server">
<script type="text/javascript" src="../examples.js"></script>
<div id="tree-div" style="overflow:auto; height:300px;width:250px;border:1px solid #c3daf9;"></div>
</form>

</body>
</HTML>js 代码
Ext.onReady(function(){
    // shorthand
    var Tree = Ext.tree;
    
    var tree = new Tree.TreePanel({
        el:'tree-div',
        useArrows:true,
        autoScroll:true,
        animate:true,
        enableDD:true,
        containerScroll: true, 
       
        loader: new Tree.TreeLoader({
            dataUrl:'/wap/Admin/left.aspx?dd=d'
        })
    });    // set the root node
    var root = new Tree.AsyncTreeNode({
        text: '管理员',
        draggable:false,
        id:'source'
    });
    tree.setRootNode(root);    // render the tree
    tree.render();
    root.expand();
});left.cs 代码
private void Page_Load(object sender, System.EventArgs e)
{
// 在此处放置用户代码以初始化页面
if (Request.QueryString["source"]!=null)
GetMenu();
}
private void GetMenu()
{
WapBLL.UserMenu objUserMenu = new XuWayMob.WapBLL.UserMenu();
DataTable dt = new DataTable();
dt = objUserMenu.GetMenu();
string js = "[";
string s = ""; BuildMenu(dt,"0",s,ref js);
Response.ContentType ="text/plain";
Response.Write(js.Substring(0,js.Length-1)+"]");
Response.End();
}输出结果如下:
[
{'text':'数据库配置','leaf':true,'cls':'file','href':'0','id':'1',
children:
[
{'text':'公司简介','leaf':true,'cls':'file','href':'/wap/CompanyProfile/CmpanyIndex.aspx','id':'3'}
]
},
{'text':'用户管理','leaf':true,'cls':'file','href':'0','id':'2',
children:[
{'text':'产品介绍','leaf':true,'cls':'file','href':'/wap/ProductsIntroduction/Products.aspx','id':'4'}
]
}
]为什么只显示出一个根目录管理员??哪出问题了?