after_validate does not stop when false is returned

class Address < ActiveRecord::Base
acts_as_mappable

belongs_to :user belongs_to :country

validates_presence_of :address validates_length_of :address, :within => 3..100

validates_presence_of :country validates_associated :country

after_validation :geocode_address

private

def geocode_address

errors.add(:address, "Could not Geocode address")
return false

end end

Using "before_validation" instead of "after_validation" works.