《ASP.NET2.0揭秘》的示例代码错误？？？

各位大侠，我在学习《ASP.NET2.0揭秘》的过程中遇到一个示例，执行总是错误。总是提示：“在建立与服务器的连接时出错。”可是这个示例并没用用到数据库。请各位能帮忙测试一下好吗？不胜感激。配置文件Web.config源码是：<?xml version="1.0"?>
<configuration xmlns="http://schemas.microsoft.com/.NetConfiguration/v2.0">
  <system.web>    <authentication mode="Windows" />
    <roleManager enabled="true" />    <siteMap defaultProvider="MySiteMapProvider">
      <providers>
        <add 
          name="MySiteMapProvider"
          type="System.Web.XmlSiteMapProvider"
          securityTrimmingEnabled="true" 
          siteMapFile="Web.sitemap" />      </providers>
    </siteMap>  </system.web>
</configuration>
站点地图文件Web.sitemap源码是：<?xml version="1.0" encoding="utf-8" ?>
<siteMap xmlns="http://schemas.microsoft.com/AspNet/SiteMap-File-1.0" >
  <siteMapNode 
    url="Default.aspx" 
    title="Home"  
    description="The Home Page">
    <siteMapNode 
      url="Products/Default.aspx" 
      title="Our Products"  
      description="Products that we offer">
      <siteMapNode 
        url="Products/FirstProduct.aspx" 
        title="First Product" 
        description="The description of the First Product" />
      <siteMapNode 
        url="Products/SecondProduct.aspx" 
        title="Second Product" 
        description="The description of the Second Product" />
    </siteMapNode>
    <siteMapNode 
      url="Services/Default.aspx" 
      title="Our Services"  
      description="Services that we offer">
      <siteMapNode 
        url="Services/FirstService.aspx" 
        title="First Service" 
        description="The description of the First Service" 
        metaDescription="The first service" />
      <siteMapNode 
        url="Services/SecondService.aspx" 
        title="Second Service" 
        description="The description of the Second Service"
        metaDescription="The second service" />
    </siteMapNode>
    <siteMapNode 
      siteMapFile="Employees/Employees.sitemap" />
    <siteMapNode 
      url="Admin" 
      title="Admin" 
      description="Administrative Pages">
      <siteMapNode 
        url="Admin/DeleteWebsite.aspx" 
        title="Delete Website" 
        description="Deletes entire Website" />
    </siteMapNode>
    <siteMapNode 
      title="External Links" 
      description="Links to external Websites" 
      roles="RoleA,RoleB,RoleC">
      <siteMapNode 
        title="Google" 
        url="http://www.Google.com" 
        description="The Google Website" 
        roles="RoleA" />
      <siteMapNode 
        title="Microsoft" 
        url="http://www.Microsoft.com" 
        description="The Microsoft Website" 
        roles="RoleB" />
      <siteMapNode 
        title="Yahoo" 
        url="http://www.Yahoo.com" 
        description="The Yahoo Website" 
        roles="RoleC" />
    </siteMapNode>
  </siteMapNode>
</siteMap>aspx页面源码是：<%@ Page Language="C#" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<script runat="server">    void Page_Load()
    {
        if (!Page.IsPostBack)
        {
            foreach (ListItem item in cblSelectRoles.Items)
                if (!Roles.RoleExists(item.Text))
                {
                    Roles.CreateRole(item.Text);
                    Roles.AddUserToRole(User.Identity.Name, item.Text);
                } 
        }
    }
    
    protected void btnSelect_Click(object sender, EventArgs e)
    {
        foreach (ListItem item in cblSelectRoles.Items)
        {
            if (item.Selected)
            {
                if (!User.IsInRole(item.Text))
                    Roles.AddUserToRole(User.Identity.Name, item.Text);
            }
            else
            {
                if (User.IsInRole(item.Text))
                    Roles.RemoveUserFromRole(User.Identity.Name, item.Text);
            }
        }
        Response.Redirect(Request.Path);
    }
    
    void Page_PreRender()
    {
        foreach (ListItem item in cblSelectRoles.Items)
            item.Selected = User.IsInRole(item.Text);
    }
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head id="Head1" runat="server">
    <style type="text/css">
        html
        {
            background-color:silver;
        }
        .column
        {
            float:left;
            width:300px;
            border:Solid 1px black;
            background-color:white;
            padding:10px;
        }
    </style>
    <title>Show Security Trimming</title>
</head>
<body>
    <form id="form1" runat="server">
    
    <div class="column">
    
    <asp:Label
        id="lblSelectRoles"
        Text="Select Roles:"
        AssociatedControlID="cblSelectRoles"
        Runat="server" />
    
    <br />
    
    <asp:CheckBoxList
        id="cblSelectRoles"
        Runat="server">
        <asp:ListItem Text="RoleA" />
        <asp:ListItem Text="RoleB" />
        <asp:ListItem Text="RoleC" />
    </asp:CheckBoxList>    
        
    <asp:Button
        id="btnSelect"
        Text="Select"
        OnClick="btnSelect_Click" 
        Runat="server" />    
    
    </div>
    
    <div class="column">
    
    <asp:TreeView
        id="TreeView1"
        DataSourceID="srcSiteMap"
        Runat="server" />
    
    <asp:SiteMapDataSource
        id="srcSiteMap"
        Runat="server" />
    
    </div>
    
    
    </form>
</body>
</html>