pagination error on heroku production server

i'm new to RoR and i'm having a paginating error on heroku production server. Development pagination works fine and i have the gem installed.

2015-05-01T15:32:09.610997+00:00 app[web.1]: ****2015-05-01T15:32:09.611002+00:00 app[web.1]: NoMethodError (undefined method paginate' for #<Class:0x00000004259be0>):**** 2015-05-01T15:32:09.603685+00:00 app[web.1]: Processing by UsersController#index as HTML 2015-05-01T15:32:09.611006+00:00 app[web.1]: 2015-05-01T15:32:09.599462+00:00 app[web.1]: Started GET "/users" for 198.84.226.196 at 2015-05-01 15:32:09 +0000 2015-05-01T15:32:09.607560+00:00 app[web.1]: Completed 500 Internal Server Error in 4ms 2015-05-01T15:32:09.611003+00:00 app[web.1]: app/controllers/users_controller.rb:9:inindex' HELP