Este RelationshipManager no puede devolver el RelatedEnd. Un RelatedEnd solo puede ser devuelto por un RelationshipManager de objetos de los que el ObjectStateManager realiza un seguimiento o que implementan IEntityWithRelationships.
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English version
The RelatedEnd cannot be returned by this RelationshipManager. A RelatedEnd can only be returned by a RelationshipManager for objects that are either tracked by the ObjectStateManager or that implement IEntityWithRelationships.
.Net Framework