FACEBOOK API GRAPH错误，无法检查设备登录状态

Question

我正在官方网站https://developers.facebook.com/docs/facebook-login/for-devices/

我有我的代码：

            do
            {                    

                UrlRequisicao = @"https://graph.facebook.com/v3.2/device/login_status?";
                UrlRequisicao = UrlRequisicao + @"access_token=37382829968|3998b73ca7a3338d390356ee987";
                UrlRequisicao = UrlRequisicao + @"&code=92a2b2e351f2b0b3503b2de251132f47"; // Example only

                var req2 = (HttpWebRequest)WebRequest.Create(UrlRequisicao);
                req2.Method = "POST";
                req2.Accept = _mediaType;
                req2.Headers.Add(HttpRequestHeader.AcceptCharset, _charSet);

                var response2 = (HttpWebResponse)req2.GetResponse();
                var bodyResposta2 = response2.GetResponseStream();
                using (var reader2 = new StreamReader(bodyResposta2))
                {
                    var jsonretorno = reader2.ReadToEnd();
                    JObject Feed = JObject.Parse(jsonretorno);
                    MessageBox.Show(jsonretorno);
                }
                System.Threading.Thread.Sleep(TimeSpan.FromSeconds(5));
            }
            while (sonda);

但是它在https://graph.facebook.com/v3.2/device/login_status?的第二个申请中给出了错误 错误如下：

  

远程服务器返回错误：（400）请求不正确。