Could not load file or assembly 'System.Net.Http.Formatting, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The system cannot find the file specified.

private Discount GetMultibuyDiscount(MultibuyBag bag)
        {
            string uri = System.Configuration.ConfigurationManager.AppSettings["Next:Use:MultibuyServiceURI"];
            var client = new HttpClient();

            var response = client.PostAsJsonAsync(uri + "Post?timeout=2000", bag).Result; //92 //5683 .PostAsJsonAsync
            if (response.IsSuccessStatusCode)
            {
                return response.Content.ReadAsAsync<Discount>().Result;
            }

            Console.WriteLine("{0} ({1})", (int)response.StatusCode, response.ReasonPhrase);
            return new Discount();

        }