Box Oauth中获取Accesstoken令牌错误

Question

请在获取代码后获取accessstoken请求通过C＃中的以下代码获取访问权限但是它总是返回我远程服务（400）错误请求

curl https://www.box.com/api/oauth2/token \
-d 'grant_type=authorization_code&code={your_code}&client_id={your_client_id}&client_secret={your_client_secret}' \
-X POST

以下是我正在使用的代码：

Stream stream = null; 
WebRequest webRequest = null; 
StreamReader streamReader = null; 
WebResponse webResponse = null; 
webRequest = WebRequest.Create("box.com/api/oauth2/token"); 

webRequest.Method = "POST"; 
webRequest.ContentType = "application/x-www-form-urlencoded";

byte[] data = Encoding.GetEncoding("UTF-8").GetBytes("'grant_type=authorization_code&code={myc??ode}&client_id={myclient_id}&client_secret={myclient_secret}'"); 
webRequest.ContentLength = data.Length; 

Stream reqstr = webRequest.GetRequestStream();

reqstr.Write(data, 0, data.Length); 
reqstr.Close();

webResponse = webRequest.GetResponse();

stream = webResponse.GetResponseStream(); 
streamReader = new StreamReader(stream);

WebResponseData = streamReader.ReadToEnd();