Live Projection that doesn't seem to work

gistfile1.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Raven.Client.Document;
using Raven.Client.Indexes;

namespace ravenplay
{
    public class Activity
    {
        public string Id { get; set; }
        public string Name { get; set; }
        public CategoryRef Category { get; set; }

    }
    public class ActivityVM
    {
        public string Id { get; set; }
        public string Name { get; set; }
        public string CategoryName { get; set; }
        public string CategoryColour { get; set; }
        public string CatId { get; set; }

    }
    public class CategoryRef
    {
        public string Id { get; set; }
        public string Name { get; set; }
    }
    public class Category
    {
        public string Id { get; set; }
        public string Name { get; set; }
        public string Colour { get; set; }
    }

    class Program
    {

        static void Main(string[] args)
        {

            using (var ds = new DocumentStore() { Url = "http://localhost:8080" })
            {
               // BuildData(ds);
                ds.Initialize();
                IndexCreation.CreateIndexes(typeof(Activity_WithCategory).Assembly, ds);
                using (var session = ds.OpenSession())
                {
                    foreach (var vm in session.Query<ActivityVM, Activity_WithCategory>().ToArray())
                        Console.WriteLine(vm.Name + "   " + vm.CategoryColour);


                }
            }
            Console.ReadLine();

        }

        private static void BuildData(DocumentStore ds)
        {
            var c = new Category() { Colour = "Green", Name = "Work-Based Learning" };
            var c2 = new Category() { Colour = "Red", Name = "Research" };


            using (var session = ds.OpenSession())
            {
                session.Store(c);
                session.Store(c2);
                session.SaveChanges();
            }
            var a = new Activity() { Name = "Learning by Doing", Category = new CategoryRef() { Id = c.Id, Name = c.Name } };
            var a2 = new Activity() { Name = "Private Study", Category = new CategoryRef() { Id = c2.Id, Name = c2.Name } };
            using (var session = ds.OpenSession())
            {
                session.Store(a);
                session.Store(a2);
                session.SaveChanges();
            }


        }
    }

    public class Activity_WithCategory : AbstractIndexCreationTask<Activity, ActivityVM>
    {
        public Activity_WithCategory()
        {
            Map = activities => from a in activities
                                select new { CatID = a.Category.Id };

            TransformResults = (db, activities) => from a2 in activities
                                                   let c = db.Load<Category>(a2.CatId)
                                                   select new { Name = a2.Name, CategoryColour = c.Colour };

        }
    }
}