Active admin forms with habtm

I have models Dealer and contact_label

class ContactLabel < ActiveRecord::Base attr_accessible :label_name, :dealer_ids end

class Dealer < ActiveRecord::Base
attr_accessible :address, :dealer_name, :dealer_image, :hidden, :dealer_type_ids, :email, :fax, :landline1, :landline2, :lat, :lon, :mobile, :working_hours

has_and_belongs_to_many :contact_labels end

In my active admin form is not displaying dealers name

 form do |f|
        f.inputs "Contact Labels" do
          f.input :label_name
          f.input :dealers, as: :check_boxes, :multiple => true
        end
        f.actions
    end

Please help me with this,...