Appointments's 'previous and next button' doesn't working

Hi, Dear WPMU.

I have another problem in using the Appointments.

The button(previous and next) doesn't working.

Here is address
http://cnisample.com/event_68/wordpress/make-an-appointment-2/

I checked the file('class_app_shortcodes.php')'s line 647 as you explained at
https://premium.wpmudev.org/forums/topic/automatic-wordpress-upgrade-may-have-messed-up-appointments-pagination?replies=6#post-780528

The file is correct. But the button doesn't working now.

I tested with Divi Theme - v.2.3.1 and I will use with this theme.
I want't it working correctly.

Solve this problem plz ASAP

Thanks for your kindness.