router scope does not behave as documented

The router documentation (http://guides.rails.info/routing.html#prefixing-the-named-route-hel...) states the following:

To prefix a group of routes, use :as with scope:

scope "admin", :as => "admin" do
  resources :photos, :accounts
end

However, when putting this code into config/routes.rb and executing rake:routes, the following is shown:

~/Code/wombat[master]% rake routes        
(in /home/rob/Code/wombat)
           GET    /admin/photos(.:format)            {:controller=>"photos", :action=>"index"}
           POST   /admin/photos(.:format)            {:controller=>"photos", :action=>"create"}
           GET    /admin/photos/new(.:format)        {:controller=>"photos", :action=>"new"}
           GET    /admin/photos/:id(.:format)        {:controller=>"photos", :action=>"show"}
           PUT    /admin/photos/:id(.:format)        {:controller=>"photos", :action=>"update"}
           DELETE /admin/photos/:id(.:format)        {:controller=>"photos", :action=>"destroy"}
           GET    /admin/photos/:id/edit(.:format)   {:controller=>"photos", :action=>"edit"}
           GET    /admin/accounts(.:format)          {:controller=>"accounts", :action=>"index"}
    admins POST   /admin/accounts(.:format)          {:controller=>"accounts", :action=>"create"}
 new_admin GET    /admin/accounts/new(.:format)      {:controller=>"accounts", :action=>"new"}
           GET    /admin/accounts/:id(.:format)      {:controller=>"accounts", :action=>"show"}
           PUT    /admin/accounts/:id(.:format)      {:controller=>"accounts", :action=>"update"}
     admin DELETE /admin/accounts/:id(.:format)      {:controller=>"accounts", :action=>"destroy"}
edit_admin GET    /admin/accounts/:id/edit(.:format) {:controller=>"accounts", :action=>"edit"}
~/Code/wombat[master]%

Instead of appending a path prefix, so for example edit_admin_account etc, it appears to be completely messing up the path names.