给TreeNode加一个TreeNode,出错的有木有.解决思路

<asp:TreeView ID="TreeView1" runat="server">
            <Nodes>
            </Nodes>
</asp:TreeView>

        protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                TreeNode root = new TreeNode("用户管理");
                TreeNode node = new TreeNode("我的空间");
                node.Target = "rightframe";
                node.NavigateUrl = "/User/Space.aspx?name=" + Session["UserName"];
                this.TreeView1.Nodes.Add(root);
                this.root.Add(node);
            }
        }