An Association with Name '{0}' on Entity (External Content Type) with Name '{1}' and Version '{2}' in Namespace '{3}' is ...

An Association with Name '{0}' on Entity (External Content Type) with Name '{1}' and Version '{2}' in Namespace '{3}' is inconsistent with the related Foreign Identifiers. If the Foreign Identifiers are on the source Entity, the Association must return a single item. If the Foreign Identifiers are on the destination Entity, the Association must return multiple items.