Installation issue?

Hello,
I've created a site in drupal 7.2 and am trying to just setup the ability for the site to subscribe users. I installed the Mail Chimp module. Everything seemed to work fine in the installation, but I've run into an issue. After installation, I go in and activate the MailChimp module. I think click 'configure' and setup the Key and save. The problem is with MailChimp Lists. I'm unable to enable it. The box is grayed out. Next to it, it says "Requires: MailChimp (enabled), Entity (missing)"

It seems the 'Entity' part is what's causing the issue. I don't know what that is and what I can do so it's not missing. I thought I could just uninstall and re-install, but uninstalling seems to have no effect- the modules are still in my list. Any ideas how I can resolve this?
Thanks!

Update: More info: there is a list created in the account as the account has been in use for over 8 months with newsletters going out.