virtualwebsource on "[Plugin: MailChimp List Subscribe Form] MailChimp plugin not working on 3.4.1"

I installed the MailChimp plugin on my WordPress multisite 3.4.1 with S2 Membership installation and activated it for the network, but it doesn't show up as a plugin on the other sites. Help?

http://wordpress.org/extend/plugins/mailchimp/