Rest Client ExecutePostAsync Error: wait for activation

Hi,

I need to establish a web api connection with restsharp. But the result I get is "wait for activation". Why does this problem occur? How can i solve it.

Is there any other way without using library.

var client = new RestClient("https://deneme.com/WebAPI/api/auth/login");
var request = new RestRequest("create", Method.Post);
request.AddHeader("Accept", "application/json");
request.RequestFormat = DataFormat.Json;
request.AddJsonBody(new { CustomerCode = "deneme", password = "deneme" });
var response = client.ExecutePostAsync(request);