accepts_nested_attributes_for is not working for uniqueness

rubyonrails-talk
1

class User < ActiveRecord::Base

accepts_nested_attributes_for :emails, :allow_destroy => true, :reject_if => proc { |attributes| attributes[‘address’].blank? }

end

class Email < ActiveRecord::Base

belongs_to :user

validates_presence_of :address

validates_email_format_of :address

validates_uniqueness_of :address, :scope=>‘user_id’

end

when i am saving multiple same emails at one time it is saving , but it should not

Please suggest what i am missing

Thanks

Rajeev sharma