MVC angularjs 404 api not found

Question

this is my webapi controller very easy:

public class TreeController : ApiController
{
    [HttpGet]
    public List<TreeData> GetTreeData()
    { 
    }
}

this is my WebApiConfig:

public static class WebApiConfig
{
    public static void Register(HttpConfiguration config)
    {

        config.Formatters.JsonFormatter.SupportedMediaTypes.Add(new MediaTypeHeaderValue("application/json"));
        config.Formatters.JsonFormatter.SerializerSettings.ContractResolver = new Newtonsoft.Json.Serialization.DefaultContractResolver();
        //config.Formatters.JsonFormatter.SerializerSettings.PreserveReferencesHandling = Newtonsoft.Json.PreserveReferencesHandling.All;
        config.Formatters.JsonFormatter.SerializerSettings.PreserveReferencesHandling = Newtonsoft.Json.PreserveReferencesHandling.None;

        // Configurazione filtro per global exception handling
       // config.Filters.Add(new WebApiUnhandledExceptionFilter());


        config.MapHttpAttributeRoutes();

        //config.Routes.MapHttpRoute(
        //    name: "DefaultApi",
        //    routeTemplate: "api/{controller}/{id}",
        //    defaults: new { id = RouteParameter.Optional }
        //);

        config.Routes.MapHttpRoute(
           name: "DefaultApi",
           routeTemplate: "api/{controller}/{action}/{id}",
           defaults: new { id = RouteParameter.Optional }
       );
    }
}

this is my angular js controller function:

    $scope.getTreeData = function () {

        $http({
            method: "GET",
            url: '/api/Tree/GetTreeData',
            dataType: "json",
        }).then(function successCallback(response) {
            $scope.data = response.data;
        }, function errorCallback(response) {
            alert("trouble..");
        });
    };

    $scope.getTreeData();

why i get 404 ? i need to configure the web.xml ? what i need to do more ?