A Schedule has a RecurringItemRange, not a RecurringItem.

app/models/recurring_item.rb

 class RecurringItem < ActiveRecord::Base
-  belongs_to :schedule
   has_many :recurring_item_ranges
 end

app/models/recurring_item_range.rb

 class RecurringItemRange < ActiveRecord::Base
+  belongs_to :schedule
   belongs_to :recurring_item
 end

app/models/schedule.rb

 class Schedule < ActiveRecord::Base
-  has_many :recurring_items
+  has_many :recurring_item_ranges
 end