[oezer]

if someone has the same problem:
mod_rewrite is enabled -> you can see it on Maintenance -> View PHP Info

but get permanently error 403, take a look on your server on /etc/apache2/*_vhost.conf file, i used a rootserver with confixx3.0

<Directory "/home/htdocs">
<Files ~ "^\.ht">
deny from all
</Files>
AllowOverride All # This one must set!
AllowOverride Indexes AuthConfig Limit FileInfo
Options None
Options +FollowSymLinks +Includes
</Directory>


<Directory "/home/htdocs/userdirectory/html">
AllowOverride All # this one
Options +FollowSymLinks +SymLinksIfOwnerMatch # and this one
<IfModule mod_access.c>
Allow from all
</IfModule>
</Directory>

and now it works fine !