El EntitySet 'X' usado para crear la expresión Ref no coincide con el EntitySet 'Y' declarado en el AssociationSetEnd 'Z' del AssociationSet 'A'.
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English version
The EntitySet 'X' used for creating the Ref expression does not match the EntitySet 'Y' declared on the AssociationSetEnd 'Z' of the AssociationSet 'A'.