Rails 3.2. Routing helper generates unvalid links

Rails 3.2. Routing helper generates unvalid links

In routes.rb:
scope "(:locale)", locale: /en|de/ do
get 'service' => 'service#index'
get 'service/:id' => 'service#show'
end
Then in view I use helper service_path(params[:locale], id) and get this
link /en/service.1. But i need link like this /en/service/1.
Check the routing via rake routes:
service GET (/:locale)/service(.:format) service#index (locale=>/en|ru/}
GET (/:locale)/service/:id(.:format) service#show
{:locale=>/en|ru/}
How to get normal links like /en/service/1, what I'm doing wrong?