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

[解决办法]
所有字符串最后怎么都有一个空格，明显不正常。