NameError (uninitialized constant ActiveMerchant::Validateable)

Question

I have integrated gem 'activemerchant', '1.50.0' in rails 4 application. In one of class I have included the ActiveMerchant::Validateable.

class Address
  include ActiveMerchant::Validateable
  attr_accessor :address1, :address2, :city, :state, :zip, :country, :first_name, :last_name, :phone
end

It gives me NameError (uninitialized constant ActiveMerchant::Validateable) error. This work fine with rails 3.2.13. Is anyone faced this issue.