ObservableCollection排序

Question

public class IPFilterRuleClass : INotifyPropertyChanged
    {
        #region 成员变量定义
        // 以字符串形式保存的ip地址，用于显示
        private string ip;
        public string IP
        {
            get { return ip; }
            set
            {
                ip = value;
                LongIP = IPtoLong(value);
                OnPropertyChanged(new PropertyChangedEventArgs("IP"));
                OnPropertyChanged(new PropertyChangedEventArgs("LongIP"));
            }
        }

        // 以字符串形式保存的url，用于显示
        private string url;
        public string Url
        {
            get { return url; }
            set
            {
                url = value;
                OnPropertyChanged(new PropertyChangedEventArgs("Url"));
            }
        }

        // 以Long型保存的IP地址，方便向SPI传递
        private long longIP;
        public long LongIP
        {
            get { return longIP; }
            set
            {
                longIP = value;
                OnPropertyChanged(new PropertyChangedEventArgs("LongIP"));
            }
        }
        #endregion

        #region 构造函数
        /// <summary>
        /// 重载后的构造函数
        /// </summary>
        /// <param name="_ip">IP地址</param>
        /// <param name="_url">Url地址</param>
        public IPFilterRuleClass(string _ip, string _url)
        {
            IP = String.Copy(_ip);
            Url = String.Copy(_url);
            LongIP = IPtoLong(_ip);
        }

        /// <summary>
        /// 默认构造函数
        /// </summary>
        public IPFilterRuleClass() { }
        #endregion

        #region 方法
        /// <summary>
        /// 将IP地址转换成Long型表示
        /// </summary>
        /// <returns></returns>
        public long IPtoLong(string DestIP)
        {
            string[] ipArr = DestIP.Split('.');

            long ip_Int = long.Parse(ipArr[3]) * 256 * 256 * 256 + long.Parse(ipArr[2]) * 256 * 256 + long.Parse(ipArr[1]) * 256 + long.Parse(ipArr[0]);
            return ip_Int;
        }
        #endregion

        #region INotifyPropertyChanged 成员

        public event PropertyChangedEventHandler PropertyChanged;
        public void OnPropertyChanged(PropertyChangedEventArgs e)
        {
            if (PropertyChanged != null)
                PropertyChanged(this, e);
        }

        #endregion
    }

我对这个创建了一个ObservableCollection<IPFilterRuleClass> IPFilterRuleList，然后想对这个列表中的元素进行排序，请问应该怎么做？

IPFilterRuleList.OrderBy<IPFilterRuleClass, string>((x) => (x.IP));不知道为啥不管用