Table Name Bug in Rails 3

application.rb

# config/application.rb

#...
config.autoload_paths += %W(#{config.root}/app/models/namespaces)
#...

exam_room.rb

# app/models/namespaces/exam_room.rb
module ExamRoom
  def self.table_name_prefix
    'exam_room_'
  end
end

exam_room_practice.rb

# app/models/namespaces/exam_room_practice.rb
module ExamRoom::Practice
  def self.table_name_prefix
    'exam_room_practice_'
  end
end

question.rb

# app/models/exam_room/practice/question.rb
class ExamRoom::Practice::Question < ActiveRecord::Base
  
end