Can't get my state_machine to Enum erate

vehicle_enum.rb

class VehicleEnum
  include DataMapper::Resource

  property :id, Serial
  property :name, String
  property :state, Enum[ :parked, :idling ]

  state_machine :initial => :parked do
    event :ignite do
      transition :parked => :idling
    end

    state :idling do
      validates_with_method :name_is_fred
    end
  end

  def name_is_fred
    return true if name == "fred"
    return [false, "Only fred can be idling"]
  end
end

fred = VehicleEnum.create({:name => 'fred'})
fred.ignite or raise "failed: couldn't ignite fred"
fred.clean? or raise "failed: couldn't save an idle fred"

wilma = VehicleEnum.create({:name => 'wilma'})
!wilma.ignite or raise "failed: could ignite wilma"
!wilma.errors.blank? or raise "failed: wilma has no errors"