Rails 3.2.12 - HTML5 - Offline cache manifest , running but no page rendered

Where am I wrong ? I should have missed some important trick… after compiling assets, and running my app in local production mode ,

going to root url =>.I just get a white page …

the console : start th render the home page then get all the cache … , and no page rendered …

>> Listening on, CTRL+  C to stop
Started GET "/" for at 2013-02-12 19:09:46 +0100
  Processing by WelcomeController#index as HTML
  .....  more ...
  Rendered welcome/index.html.haml within layouts/application (438.3ms)
  Completed 200 OK in 3700ms (Views: 539.7ms | ActiveRecord: 101.8ms)
  Started GET "/fr/application.manifest" for at 2013-02-12 19:09:51 +0100
# b674b99ed2e29478bf9b8887fd1448dcd5755e2b2f8882a9abf2030d70ae5ae5
  offline.  html
assets/application-cb5548d93b80852ceb169309f728eb75.  js .... more assets ....

In my application.html.haml

 %html{:lang => "en", :manifest => manifest_path }

In my routes.rb

  Rack::Offline.configure do
    cache "assets/application.js"
    cache "assets/application.css"
    network "/"
  match "/application.manifest" => Rails::Offline, :as => :manifest

In my mimes_types.rb

Mime::Type.register "text/cache-manifest", :manifest