Fixtures Load Error

When I run the following file:
  
require 'active_record/fixtures'
  require 'Order'
  
    class LoadOrdersData < ActiveRecord::Migration
      def self.up
        down
          f = Fixtures.new(Orders.connection, # a database connection
                          "orders", # table name
                           Order, # model class
                           File.join(File.dirname(__FILE__), "dev_data/orders"))
          f.insert_fixtures
    end

    def self.down
      Order.delete_all
    end
  end

I am getting the following error:

LoadError: no such file to load — active_record/fixtures

method require in 003_load_orders_data.rb at line 1
at top level in 003_load_orders_data.rb at line 1

I ran the rake rails:freeze:edge but it gives the same error message. How can I fix this error? TIA.