CSS issue when using SubUri and Passenger

I am testing another application in local

in my environment.rb I wrote
config.action_controller.relative_url_root = "/elnino"
config.action_controller.asset_host = "http://opticoaching.local"

I defined correctly the vhost (I have already odne it for another app
which is running well...)
<VirtualHost *:80>
  ServerName opticoaching.local
   DocumentRoot "/Users/yves/Sites/rails/opticoaching"

    RailsEnv development
    RailsDefaultUser yves
    RailsBaseURI /elnino

    <Directory /Users/yves/Sites/rails/opticoaching/elnino/public/ >
    Options Indexes FollowSymLinks MultiViews
    AllowOverride All
    </Directory>

</VirtualHost>

opticoaching.local is registered (as usual) in my etc/hosts

executing http://opticoaching.local/elnino, the CSS and images are not
taken in account ..

http://opticoaching.local/elnino/
http://opticoaching.local/images/elnino.jpg
http://opticoaching.local/stylesheets/application.css

what could be wrong ?

I already did it for another application without any problem ..
cannot find the differences...

thanks for you suggestions

SOLVED ... discover some CSS link redefinition missing the relative
URL root !!