抓包工具,HttpWebResponse获取其他网站图片问题

[待解决问题]

当我把抓包工具打开时,就能正常获取其他网站图片,但是当我把抓包工具关闭时,HttpWebResponse httpWebResponse = (HttpWebResponse)httpWebRequest.GetResponse(); 就提示说"基础连接已关闭,基础连接已经关闭: 接收时发生错误。"

 Uri url = new Uri("");
                HttpWebRequest httpWebRequest = (HttpWebRequest)WebRequest.Create(url);
                httpWebRequest.KeepAlive = true;
                httpWebRequest.ProtocolVersion = HttpVersion.Version11;
                httpWebRequest.Method = "GET";
                httpWebRequest.Accept = "*/* ";
                httpWebRequest.UserAgent = "Mozilla/5.0 (Windows NT 6.1) AppleWebKit/536.5 (KHTML, like Gecko) Chrome/19.0.1084.56 Safari/536.5";
                httpWebRequest.Referer = caijiUrl;
                httpWebRequest.ContentType = "keep-alive";
                httpWebRequest.Host = "t5.mangafiles.com";
                HttpWebResponse httpWebResponse = (HttpWebResponse)httpWebRequest.GetResponse();
                System.Drawing.Image img;
                img = new System.Drawing.Bitmap(httpWebResponse.GetResponseStream());