Gem failing when using with nested activeadmin resources

[delphist]

I have a HelpCategory resource:

ActiveAdmin.register HelpCategory, namespace: :admin do
  reorderable

And nested HelpAnswer resource:

ActiveAdmin.register HelpAnswer, namespace: :admin do
  belongs_to :help_category
  reorderable

And when i get into /admin/help_categories/1/help_answers page I getting this error:

undefined method `reorder_admin_help_answer_path'

Simply, it should use reorder_admin_help_category_help_answer_path, but it doesn't