WCF RIA collection property isn't included
===

I have hierarchical QueryElement entity. I'm trying to get hierarchy on Silverlight client side:

    public IQueryable<QueryElement> GetQueryElements()
    {
      return this.ObjectContext.QueryElements.Include("Children").Where(x => x.ID == 2);
    }

Metadata Include attribute is set:

    internal sealed class QueryElementMetadata
    {
      [Include]
      public EntityCollection<QueryElement> Children;
    }

But on the client side only element with ID = 2 is returned and its `Children` collection is empty.  I've checked on the server side and Children collection have `IsLoaded` = true and contains elements, so the problem seems to be in WCF RIA but I cannot figure out what I'm doing wrong.