BadRequestError while generating access token

[Kamal]

It works fine on PostMan and  restClient but fails in my Xamarin.Android code. Please advise.

JSON input:

JSONObject jsonObject = new     JSONObject ();
            jsonObject.Put ("client_id","OTk3NGQzNmUtYmE4NS00NjA5LTkwYmItZGJkZmU1YTAxODlj");
            jsonObject.Put ("client_secret","NTg5M2Q5N2YtZGI4OS00Y2I1LWJjNDUtYjE0Y2ZhMGIxYTc4");
            jsonObject.Put ("response_type","code");
            jsonObject.Put ("grant_type","authorization_code");
            jsonObject.Put("redirect_uri","http://yourdomain.com/somepath?code=YmJkYzJmNTItZDA4My00NGJhLWJhZTgtZjZlYjcwZDZiZjYz");

            jsonObject.Put("code","YmJkYzJmNTItZDA4My00NGJhLWJhZTgtZjZlYjcwZDZiZjYz");  

            var client = new RestClient ("https://api.rhapsody.com/oauth/access_token");
            var request = new RestRequest ("", RestSharp.Method.POST);
            request.AddParameter("application/Json", jsonObject.ToString(), ParameterType.RequestBody);
            var response =   client.Execute (request);
            var content = response.Content;
            Console.WriteLine("Result->"+content);  

Response:

{"code":"BadRequestError","message":"No client ID supplied"}

Thanks

Kamal