關於C#代理上網的問題，救命呀

Question

try
                {
               string urlStr = "http://www.sohu.com";                            //設定要獲取的地址
                    HttpWebRequest hwr = (HttpWebRequest)HttpWebRequest.Create(urlStr);    //建立HttpWebRequest對象
                    hwr.Method = "GET";
                    hwr.Timeout = 60000;                                                //定義服務器超時時間
                    WebProxy proxy = new WebProxy();                                    //定義一個網關對象
                    proxy.Address = new Uri("http://202.98.23.114:80");            //網關服務器:端口
                    proxy.Credentials = new NetworkCredential(null, null); 
                    //用戶名,密碼
                    hwr.UseDefaultCredentials = true;                                    //啟用網關認証
                    hwr.Proxy = proxy;  
                                                  //設置網關
                    
                    HttpWebResponse hwrs = (HttpWebResponse)hwr.GetResponse();            //取得回應
                    Stream s = hwrs.GetResponseStream();                                //得到回應的流對象
                    StreamReader sr = new StreamReader(s, Encoding.UTF8);                //以UTF-8編碼讀取流
                    StringBuilder content = new StringBuilder();                        //
                    while (sr.Peek() != -1)                                                //每次讀取一行,直到
                    {                                                                    //下一個字節沒有內容
                        content.Append(sr.ReadLine() + "\r\n");                            //返回為止
                    }                                                                    //                }
                catch (Exception ek) {                    Console.WriteLine(ek.ToString());
                }以上代嗎怎麼報 The remote server returned an error: (503) Server Unavailable.這個錯誤呀，
我用IE設就可以用，程序就不可以了呀，