Hello, I fixed the issues :D The problem was that there is is a url rewrite and MapRoute that redirect the call of Web Services to _mvc/Default in UsiteModelBuilder project so the call get 404. So I add MapRoute for BackOfficeApi url.

And the result is from

    public class RegisterMVCRoutes
{
    public static void Setup()
    {

        RouteTable.Routes.MapRoute(
            "mvc", // Route name
            "_mvc/{culture}/{controller}/{action}/{id}", // URL with parameters
            new { controller = "Home", action = "Index", culture = "Default", id = UrlParameter.Optional } // Parameter defaults
            );
    }
}

To

    public class RegisterMVCRoutes
{
    public static void Setup()
    {
        RouteTable.Routes.MapHttpRoute(
                name: "BackOfficeApi",
                routeTemplate: "umbraco/BackOffice/Api/{controller}/{action}/{id}",
                defaults: new { id = RouteParameter.Optional }
            );
        RouteTable.Routes.MapRoute(
            "mvc", // Route name
            "_mvc/{culture}/{controller}/{action}/{id}", // URL with parameters
            new { controller = "Home", action = "Index", culture = "Default", id = UrlParameter.Optional } // Parameter defaults
            );
    }
}

Thank you all
Oussama