json posing is not working in web services, asp.net

[WebMethod]
   [ScriptMethod(ResponseFormat = ResponseFormat.Json)]
   public string GetJSONString2()
   {
       prodoct p = new prodoct();
       p.i = 500;
       p.j = 1000;
       string str = JsonConvert.SerializeObject(p);
       return str;
   }

prodoct p = new prodoct();
p.i = 5;
p.j = 10;


string data = JsonConvert.SerializeObject(p);

WebClient webClient = new WebClient();
//webClient.Headers.Add("Authorization", "Bearer " + accesstoken);
webClient.Headers.Add("Content-Type", "application/json");
webClient.Headers.Add("User-Agent", "CreditCard Authorize");
string json = "";

string URI = "http://localhost:57084/CreateWebService/Service.asmx";
json = webClient.UploadString(new Uri(URI + "?GetJSONString2"), "POST", data);
var jsonres = JsonConvert.DeserializeObject<prodoct>(json);


Stream stream = webClient.OpenRead(json);
StreamReader reader=new StreamReader(stream);
String request = reader.ReadToEnd();
Response.Write(request);