error appearing as (OAuthException - #803) (#803) Some of the aliases you requested do not exist: messages

var parameters = new Dictionary<string, object>();

            parameters["messaging_type"] = "response";


            parameters["recipient"] = replyBy;


            parameters["message"] = status;


            var result = (IDictionary<string, object>)(await 

app.PostTaskAsync("/" + "/messages", parameters));