how to send MyType.List<MyOtherType> with WCF RIA Services

Question

How to send Points from below Result class with RIA services ?

I've tried what's written below but it doesn't work. (Only one Point is sent from Points collection !?)

public class Result
{
   [KeyAttribute]
   public double Key {get;set;}

   [Include]
   [AssociationAttribute("AssociationName", "Key", "Key")]   
   public List<Point> Points {get;set;}
}

where Point is declared as:

public class Point
{

[KeyAttribute]
public double Key { get; set; }

public double X { get; set; }

public double Y { get; set; }
}