网络编程的一个问题


  Encoding   encoding   =   Encoding.GetEncoding( "GB2312 ");                               
                                string   strUrl   =   @ "http:// "   +   DefaultIP   +   " "   +   DefaultUrl   +   " "; 
                                string   postData   = "username= "+UserName+ "&password= "+password+ "&area_c=&telfile1= "+TelePhones+ " ";                               
                                byte[]   data   =   encoding.GetBytes(postData); 
                                //   准备HTTP请求... 
                                System.Net.HttpWebRequest   myRequest   =   (System.Net.HttpWebRequest)System.Net.WebRequest.Create(strUrl); 
                                myRequest.Method   =   "POST "; 
                                myRequest.ContentType   =   "application/x-www-form-urlencoded "; //运行提示无法按照请求设置空的或空白的方法
                                myRequest.ContentLength   =   data.Length; 
                                System.IO.Stream   newStream   =   myRequest.GetRequestStream(); 
                                //   发送数据 
                                newStream.Write(data,   0,   data.Length); 
                                newStream.Close(); 
                                //HTTP响应 
                                System.Net.HttpWebResponse   myResponse   =   (System.Net.HttpWebResponse)myRequest.GetResponse(); 
                                System.IO.Stream   receiveStream   =   myResponse.GetResponseStream(); 
                                Encoding   encode   =   System.Text.Encoding.GetEncoding( "GB2312 "); 
                                System.IO.StreamReader   readStream   =   new   System.IO.StreamReader(receiveStream,   encode); 
                                Char[]   read   =   new   Char[256]; 
                                int   count   =   readStream.Read(read,   0,   256); 
                                StringBuilder   sb   =   new   StringBuilder( " "); 
                                while   (count   >   0) 
                                { 
                                        String   readstr   =   new   String(read,   0,   count); 
                                        sb.Append(readstr); 
                                        count   =   readStream.Read(read,   0,   256); 
                                } 
                                myResponse.Close(); 
                                readStream.Close(); 运行到 myRequest.ContentType   =   "application/x-www-form-urlencoded ";提示我无法按照请求设置空的或空白的方法，不知道怎么解决。另外我想用这个代码写91基金的接口，懂得能和我说说能成不网络编程无法按照请求设置空的或空白的方法接口