Line 15 throws the error

base_controller.rb

class BaseController < ApplicationController
  require 'simplepay/authentication'  
  require 'simplepay/rails'      
  
  before_filter :add_admin_links
  before_filter :add_subscription_return_url

  private
    def add_admin_links
      links = [
          {:name => :'activerecord.models.subscription'.l(:count => 'many'), :url => subscriptions_url},
          {:name => :'activerecord.models.user_subscription'.l(:count => 'many'), :url => user_subscriptions_url}
        ]

      @admin_nav_links = @admin_nav_links + links
    end  

    def add_subscription_return_url
      if params[:subscription_return_to]
        session[:subscription_return_to] = params[:subscription_return_to] 
        session[:return_to] = params[:subscription_return_to]         
      end
    end
  
end