HTTPS vs HTTP error with Appointments +

I am having a problem with the Appointments + plugin on my site here: http://sites.ap.buffalo.edu/schedule-a-tour/

I have attached an image of the debug from Firefox.

I believe that the js-check.js is having a problem with rectifying that our backend if secured with HTTPS.

If you edit the URL about to include HTTPS....the plugin works but without it, nothing happens when you click on an available time slot.