What is the proper way of defining related collections in code first Entity Framework 5?
I was following this [summary](http://blogs.msdn.com/b/efdesign/archive/2010/06/01/conventions-for-code-first.aspx?Redirected=true) but something is not working.

I have the following model:

```
class Order
{
  public Guid Id {get; set; }
  public DateTime Created {get; set;}
  public ICollection<OrderLine> OrderLines {get; set;}
}

class OrderLine
{
  public Guid Id {get; set;}
  public Guid OrderId {get; set;}
  public Order Order {get; set;}
  public string Product {get;set;}
}

class OrderContext : DbContext
{
    public DbSet<Order> Orders { get; set; }
    public DbSet<OrderLine> OrderLines { get; set; }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        modelBuilder.Conventions.Remove<PluralizingTableNameConvention>();

        base.OnModelCreating(modelBuilder);
    }
}

```

There is an `Order` with some lines in the database. When it is loaded it's `OrderLines` property is null. 

I have tried making `OrderLines` virtual, it did not help.
Otherwise, everything is set to default. Lazy load is true, CreateProxy is true...

When I try to `Include("OrderLines")` it works and fetches the lines from DB.