Adding a site doesn't seem to work.

Hello,
I am having some troubles using the multisite fonctionnality.
I have a fresh install on a my test server, I created a network following this : http://codex.wordpress.org/Create_A_Network . So multisite is activated, when I go to admin’s dashboard of the network and I add a new site, I can see it in the list of my site. But when I try to access to this site or its dashboard I get a 404 error.

Permalinks are set to default. It is subfolder network.
I try to reinstall wordpress 3 times thinking I might missed something. But I can’t see what is wrong.

Here is my htaccess:

<IfModule mod_rewrite.c>
  RewriteEngine On
  RewriteBase /LibelMultiSite/
  RewriteRule ^index\.php$ - [L]

  # add a trailing slash to /wp-admin
  RewriteRule ^([_0-9a-zA-Z-]+/)?wp-admin$ $1wp-admin/ [R=301,L]

  RewriteCond %{REQUEST_FILENAME} -f [OR]
  RewriteCond %{REQUEST_FILENAME} -d
  RewriteRule ^ - [L]
  RewriteRule ^([_0-9a-zA-Z-]+/)?(wp-(content|admin|includes).*) $2 [L]
  RewriteRule ^([_0-9a-zA-Z-]+/)?(.*\.php)$ $2 [L]
  RewriteRule . index.php [L]
</IfModule>

And my wp-config.php

define( 'WP_ALLOW_MULTISITE', true);
define('MULTISITE', true);
define('SUBDOMAIN_INSTALL', false);
define('DOMAIN_CURRENT_SITE', 'sdebian');
define('PATH_CURRENT_SITE', '/LibelMultiSite/');
define('SITE_ID_CURRENT_SITE', 1);
define('BLOG_ID_CURRENT_SITE', 1);

Thanks