ruby-on-rails - Rails gem: Cancan on production is not working

Question

I'm using cancancan.. and it works fine on development env .. but once i got it on the production the site works like if there's no gem installed at all.. no authorization handled.

I can't figure out what is wrong

--------------------edited in the application controller there's

before_filter :authenticate_user!, if: :devise_controller?

rescue_from CanCan::AccessDenied do |exception|
  # Make sure we don't redirect to an HTML page
  # in API requests because this is absolutely a bad idea
  unless request.accept == 'application/json'
    flash[:error] = "Access denied."
    redirect_to root_url
  end
end

and in the ability file

def initialize(user)
  # Define abilities for the passed in user here. For example:
  #
  user ||= User.new # guest user (not logged in)
  if user.admin?
    can :manage, :all
  else
    can :index, Book
    can :index, Category 
  end
end