Ask Seller A Question Notification Not Appearing?

Hello, I've been testing out the 'Ask Seller a Question' addon and as I understand it, there's supposed to be a notification to the vendor when a new message is sent. In my Administration -> Notifications settings the Notifications Center option is checked, at the 'New message received' row, but I'm still not getting any notifications, why is that?

I'm using the old emailing system, but the user guide said that email notifications wouldn't work with that, it didn't say anything about the notifications center.