Who can explain why loading the fixture generates: Couldn't call Doctrine_Core::set(), second argument should be an instance of Doctrine_Record or Doctrine_Null when setting one-to-one references (or one-to-many).
I was using my own schema and decided to simplify things by using a simple schema from the doctrine documentation. But the error is still occurring. It occurs when the data for phonenumbers tries to load from the fixture. See below: