"Next Week/Month" Button is not working on Appointments+

This week I installed the Appointments+ plugin on my personal website (www.DavidRobertson.biz/make-an-appointment/) to work with my personal gmail calendar. It syncs perfectly, and I am really excited to roll it out to our MU network. However, I am experiencing a but that I've not been able to fix in the settings...

The "Next Week" or "Next Month" button does not bring up the next week or month calendar. The only thing that happens is that current month/week calendar is repositioned at the top of the screen, but the dates do not actually change.

Could someone please provide some assistance in how I can fix this issue? You can see the calendar at http://www.davidrobertson.biz/make-an-appointment/