Need help with nested resource and link_to

I've read all the posts, blogs, peepcode about nested resources but I
can't get link_to to work. I know I'm missing something simple so I
hope another set of eyes will help out.

I have a pretty simple set up:

deliverable has_many :roles

role belongs_to :deliverable

here is what I have in routes.rb:
map.resources :deliverables, :has_many => :roles

from views/deliverables/show.html.erb I'm trying to provide a link to
add a new role with this:

<%= link_to "+ Add Role", new_role_url(@deliverable) %>

But I get this error when rendering: undefined method `new_role_url'

I can type in the url http://localhost:3000/deliverables/1/roles/new
and it works fine so I'm stumped.

Thanks in advance for the help.

rails 2.0.2
ruby 1.8.6

figured it out by checking out rake routes. should be:

<%= link_to "+ Add Role", new_deliverable_role_path(@deliverable) %>