Questions About Helper Module in Rails

I tried to create a helper module for my Rails application. I included the module in my model, created some new method using functions from the module and it works in the controller. However, it raise an exception when I try to view a page who use the model.

Here is the details:

First, I created the helper module. The file name is "lib/data_query.rb".

module DataQuery
  def foo
    return 42
  end 
end

Second, I modified the file "config/application.rb"

config.autoload_paths += %W(#{config.root}/lib/)

The model which will be using this module is called App. I included the module and built new methods on the module function

class App < ActiveRecord::Base
  include DataQuery
  # ...... other method ...

  def bar
   # function from DataQuery
    return foo
  end 
end

I run it in the Rails console and it works.

App.new.foo # it works

However, I have a controller and view called Report. In report#index, I have an instance variable called

def index
  @app = App.find(1)
end

When I atttempted to open the view, an exception shows up: "uninitialized constant App::DataQuery"

Any suggestions?