undefined method `per_page_kaminari' for #<ActiveRecord::Relation []> fi...

Hi guys,

as I am trying to use active admin, I got this error on freshly installed active_admin

my app is using  will_paginate, so I set it up like you say here 
https://github.com/gregbell/active_admin/wiki/How-to-work-with-will_paginate
and the I got this problem, hope it helps someone :)