Ember (belongsTo and hasMany) association not working

It always returns null, when I tried with another 'find' call it returns me a promised array, which is useless for me. I can't use it as a relation in views.

App.Truck = DS.Model.extend job: DS.belongsTo('job', { async: true })

App.Job = DS.Model.extend trucks: DS.hasMany('truck', { embedded: 'always' })