enable CORS setting for soap web service on visual studio development server

i am trying to add CORS setting by enabling "Access-Control-Allow-Origin" header in Web Service method shown below. However, I'm still getting error: No 'Access-Control-Allow-Origin' header is present on the requested resource.' Am i missing anything?

        [ScriptMethod(UseHttpGet = true)]
        [WebMethod]
        public ClientData[] GetClientData(int Number)
        {

            HttpContext.Current.Response.AddHeader("Access-Control-Allow-Origin", "http://localhost:52630");

            ClientData[] Clients = null;

            if (Number > 0 && Number <= 10)
            {
                Clients = new ClientData[Number];
                for (int i = 0; i < Number; i++)
                {
                    Clients[i].Name = "Client " + i.ToString();
                    Clients[i].ID = i;
                }
            }

            return Clients;
        }