htaccess Elite

Hello I'm having a problem with a htaccess file.
I wants to have an dynamic subdomain for every directory in domain.com/users.
But it doesn't work like wanted.
I want it like domain.com/users/username to username.domain.com

This is my script so far:

ServerAlias *.klupje.nl
Options +FollowSymLinks
Options +Indexes
RewriteEngine On
RewriteCond %{HTTP_HOST} ^([^.]+).domain.com$
RewriteCond %{1} !^(www|example|includes|images| )$
RewriteCond /var/www/vhosts/domain.com/httpdocs/users/%1 -d
RewriteCond %{REQUEST_FILENAME} !^/var/www/vhosts/domain.com/httpdocs/users/
RewriteRule ^(.*)$ /users/$1 [L]