我在my_app_root / public / stylesheets / screen.css和我的application.html.erb中有“screen.css”

<%= stylesheet_link_tag 'screen.css',:media => 'screen' %>

根据here它应该工作,但我的rails服务器说：

Processing by PagesController#home as HTML
Rendered pages/home.html.erb within layouts/application (0.0ms)
Completed 200 OK in 4ms (Views: 3.6ms | ActiveRecord: 0.0ms)

Started GET “/assets/screen.css” for 127.0.0.1 at 2011-06-18 11:27:53 +1200
Served asset /screen.css – 404 Not Found (2ms) (pid 10966)

ActionController::RoutingError (No route matches [GET] “/assets/screen.css”):

我在这里做错了什么？

提前致谢