Broken URL due

Hello,

I have just installed WP mu and changed the htaccess file as below :
-------------------------
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]

# uploaded files
RewriteRule ^files/(.+) wp-includes/ms-files.php?file=$1 [L]

RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^ - [L]
RewriteRule . index.php [L]

<IfModule mod_security.c>
<Files async-upload.php>
SecFilterEngine Off
SecFilterScanPOST Off
</Files>
</IfModule>
----------------------
Is it the appropriate code ?
All my url are broken. I have a VPS and I already have activated mod_rewrite in my webmin. "Wildcards subdomain" is activated.

I have configured config.php also :
define('WP_DEBUG', false);
-------------------
define( 'MULTISITE', true );
define( 'SUBDOMAIN_INSTALL', true );
$base = '/';
define( 'DOMAIN_CURRENT_SITE', 'www.mysite.com' );
define( 'PATH_CURRENT_SITE', '/' );
define( 'SITE_ID_CURRENT_SITE', 1 );
define( 'BLOG_ID_CURRENT_SITE', 1 );

define( 'SUNRISE', 'on' );

/* That's all, stop editing! Happy blogging. */
---------------
Is it the good code ?

Do I have to set some additional options to use MU and rewrite mode, on a VPS ?

I would need your help, thank you

Christop2