I'm trying to create a very simple relationship between two objects. Can anybody explain me why I can't find the Company object via findBy method?

class Company {
    String name
    String desc
    City city
    static constraints = {
        city(unique: true)
    }
}
class City {
    String name
    static constraints = {
    }
}
class BootStrap {
    def init = { servletContext ->
        new City(name: 'Tokyo').save()
        new City(name: 'New York').save()

        new Company(name: 'company', city: City.findByName('New York')).save()

        def c = Company.findByName('company') // Why c=null????!
    }
    def destroy = {
    }
}