How to: Nullable Relationships?

Hello all!

For example, suppose that I have a class named "Left" and this class has a relation with a "Right" class, but is not required: 

[Association(Name = "FK_Left_Right", Storage = "_Right", ThisKey = "RightID")] public Right Right{    get   {return this._Right.Entity;} // error line    set {...} }

When the relation property is null DLINQ throws a EmptySequenceException!

The error occurs in two cases:

   - When the property it' called directly, example: "_Left.Right"

   - When other property it's changed, example: "_Left.Other = value", in this case it's threw through the OnChanging Event

How can I use nullable relationships

Thanks and excuse my English
 
Vitor