Different versions?

I’ve had great success with this plugin on a website I’ll call Site1. I like the way it works: intuitive, easy and handy.

I recently (and I think successfully) installed this plugin on a site I’ll call Site2.

I think I’ve successfully installed (to be honest the installation guide was a little lacking). However, this new install doesn’t work like the old install. The Site1 install has a domain mapping tab until Tools on every single site. Site1’s admin panel shows the plugin under “MUST USE” but Site2 does not.

Any helps is appreciated.

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