new addon domain does not appear on multi site

It won’t.

1) Activate Multisite
2) Create a subsite (domain.com/sub or sub.domain.com)
3) Install domain mapping
4) Inside WP, map the new domain to the sub site
5) Make sure you add the domain to your server, dns, etc.

http://wordpress.org/extend/plugins/wordpress-mu-domain-mapping/