一个项目需要用到TreeView需要多个属性 ,我想把这些属性存放到treeNode中 我打算继承他来使用,但是发现不行

    public class FileNode:System.Web.UI.WebControls.TreeNode
    {

        private string _fatherId;

        public string FatherId
        {
            get { return _fatherId; }
            set { _fatherId = value; }
        }
        private string _orderId;

        public string OrderId
        {
            get { return _orderId; }
            set { _orderId = value; }
        }

        public FileNode():base()
        {

        }

        public FileNode(string text,string value,string father,string order):base(text,value)
        {
         
            this.FatherId = father;
            this.OrderId = order;
           
           
        }

        protected override object SaveViewState()
        {
            object[] arrState = new object[5];
            arrState[0] = base.SaveViewState();
            arrState[1]=this.Text;
            arrState[2] = this.Value;
            arrState[3] = this.FatherId;
            arrState[4] = this.OrderId;
            return arrState;
        }

        protected override void LoadViewState(object savedState)
        {
            if (savedState != null)
            {
                object[] arrState = savedState as object[];

                this.Text = (string)arrState[1];
                this.Value = (string)arrState[2];
                this.FatherId = (string)arrState[3];
                this.OrderId = (string)arrState[4];
                base.LoadViewState(arrState[0]);
            }
        }

    }

用的时候 string aaa = (TreeView1.Nodes[0] as FileNode).OrderId;

发现根本不行  

请问谁有办法啊  谢谢