acl_system2 : undefined method `access_control'

I am using acl_system2 plugin to implement my authorization. (with
restful_authentication plugin)

- plugin install
./script/plugin install
http://opensvn.csie.org/ezra/rails/plugins/dev/acl_system2

- class UsersController < ApplicationController
access_control :new => '(admin)'

- error
undefined method `access_control' in UsersController

Please help me, advanced!
thanks