DataContractSerializer not serializing all properties of a custom object within collection

I have the following classes:

[Serializable] 
[DataContract(Name = "LayerInfo", Namespace = "ems.gis")]  
public abstract class LayerPersistInfo
{ 
    public 开发者_如何学JAVALayerPersistInfo()  { }      
    public LayerPersistInfo(int index, MappingContextBase context) 
    {
      Index = index;
      Context = context;
    }

     [DataMember(Name="idx", Order=0)]  
     public int Index { get; set; }  

    //[DataMember(Name = "name")] 
    //public string Name { get; set; }

    [DataMember(EmitDefaultValue = true, Name="ctx", Order=1)]  
    public MappingContextBase Context { get; set; } 

    [DataMember(EmitDefaultValue = false, Name="lyrs", Order=2)]  
    public LayersPersistInfo Children { get; set; }      

    public abstract TocItemModel GetLayerModel();  

 }

[Serializable] 
[CollectionDataContract(Name = "lyrs", Namespace = "ems.gis", ItemName = "lyr")]  
public class LayersPersistInfo : List<LayerPersistInfo> 
{

}

Multiple instances of concrete implementations of the abstract LayerPersistInfo class end up in LayersPersistInfo which I need to serialize. What I am observing is very strange.

If LayersPersistInfo has 2 or more items with children, the Context property of each child of the element at index 0 is null. On the next serialization attempt after repopulating the collection, Context property of each child of the element at index 1 of LayersPersistInfo is null . On the next attempt, children of item 0 all have null Context and so on . This behaviour is very consistent.

If my custom collection LayersPersistInfo has just one item, all children are properly serialized.

I have put a break point just before calling WriteObject on the serializer instance and these property is never null. What could I possibly be doing wrong here?

TIA.

My fault. Was not using Context property properly after data was deserialized.