I am working on MVC5. I just Added a API Controller & facing error in WebApiConfig. The Error is- ambiguous reference system web http routeparameter. I don't understand from where Ambiguity is creating. Can any one please explain??

MyCode is:

```
using System.Web.Http;
namespace MyProject
{
    public static class WebApiConfig
    {
        public static void Register(HttpConfiguration config)
        {
            config.MapHttpAttributeRoutes();
            config.Routes.MapHttpRoute(
                name: "DefaultApi",
                routeTemplate: "api/{controller}/{id}",
                defaults: new { id = RouteParameter.Optional }
            );
        }
    }
}

```