Email notifications for comments on a multisite

I have an author that wants to be emailed when users comment on her posts. WordPress doesn't do this for authors, only admins. So, I downloaded a plugin (cbnet Multi Author Comment Notification) to resolve the issue. This didn't work either (not sure why).
My question is that at the network level, the email notifications are checked. But, at the site level WP will not let me check them. I have a feeling that this is why the plugin is not working. In the plugin FAQ it says that these much be checked. Can you tell me why I can't check them at the site level?
Also, can you recommend a solution for me? Maybe a different plugin or another work around? Thanks.