Nested routes and a missing method

I have this nested route:

map.resource :users do |user|
  user.resources :roles
end

Which, among others, gives me this named routing, user_roles:

    user_roles GET /users/:user_id/roles
(.:format)
                             {:controller=>"roles", :action=>"index"}

However, when I try using "link_to to user_roles" I get this method
missing error. What am I doing wrong?

NameError in Users#show

Showing app/views/users/show.html.erb where line #59 raised:

undefined local variable or method `user_roles' for #<ActionView::Base:
0x2aaaac0c3bf0>

Extracted source (around line #59):

57:
58: <%= link_to 'View This Account\'s Assigned Roles',
59: user_roles,
60: :id => 'user_roles_link'%>
61:

Should be instead:

57:
58: <%= link_to 'View This Account\'s Assigned Roles',
59: user_roles_path,
60: :id => 'user_roles_link'%>
61:

Sigh...