Unable to activate Mail Chimp Sync.

Greetings. I have the plugin installed and Network Activated, yet on my list of plugins on the site, everything is listed as an option to activate except MailChimp. The folder mailchimp-sync is in the plugins directory on the server.

I have tried everything I know, including clearing everything, rebooting, different browsers - nothing. Any ideas would be greatly appreciated.

Cheers. - Frank