Composition and RIA

i have problems with related properties Composition attribut and RIA.I 'm using POCO and silverlight. here is my modele :

[MetadataTypeAttribute(typeof(ModeleEnvoiEaMetaData))]
    [Serializable]
    public abstract partial class ModeleEnvoiEa
    { 
        [DataMember]
        public virtual int IdModeleEnvoiEa {get;set;}
        [DataMember]
        public virtual string Libelle {get;set;}
        [DataMember]
        public virtual Nullable<int> IdModeleEnvoiEaFooter  {...//FK }
        public virtual ModeleEnvoiEaHeaderFooter ModeleEnvoiEaFooter
        {
            get { return _modeleEnvoiEaFooter; }
            set
            {
                if (!ReferenceEquals(_modeleEnvoiEaFooter, value))
                {
                    var previousValue = _modeleEnvoiEaFooter;
                    _modeleEnvoiEaFooter = value;
                    FixupModeleEnvoiEaFooter(previousValue);
                }
            }
        }
        private ModeleEnvoiEaHeaderFooter _modeleEnvoiEaFooter;
     }

public partial class ModeleEnvoiEaMetaData
    {
//...
[Association("ModeleEnvoiEa_ModeleEnvoiEaFooter","IdModeleEnvoiEaFooter","IdModeleEnvoiEaHeaderFooter")]
        [Include]
      开发者_StackOverflow  [Composition]
        public ModeleEnvoiEaHeaderFooter ModeleEnvoiEaFooter;    
}

}

In client side i call Test domaine service method , in the client side the property ModeleEnvoiEaFooter is not null, but in my DomainServices class this property is null. Even with de Composition attribut. How can i send the value of ModeleEnvoiEaFooter property to Domainservices class ?

 [Invoke]
 public ModeleEnvoiEa Test(ModeleEnvoiEa modele)
 {
  // modele.IdModeleEnvoiEaFooter   == 1 // FK to ModeleEnvoiEaFooter 
  // modele.ModeleEnvoiEaFooter is null here ! Why ? an how can i send this object 
 }

Try marking ModeleEnvoiEaFooter as a DataMember.