Appointment+ can not update a page, there's an error. :(

Hello there,

Hope you're having a beautiful day,

I'm having trouble with my site, I keep trying to update my page but I keep having trouble :slight_frown:
Any help would be greatly appreciated.
Here's the error message I keep getting on a blank screen right after clicking update:

Warning: Cannot modify header information - headers already sent by (output started at /home/koalatutor/public_html/wp-content/plugins/appointments/includes/shortcodes/class-app-shortcode-confirmation.php:187) in /home/koalatutor/public_html/wp-admin/post.php on line 197

Warning: Cannot modify header information - headers already sent by (output started at /home/koalatutor/public_html/wp-content/plugins/appointments/includes/shortcodes/class-app-shortcode-confirmation.php:187) in /home/koalatutor/public_html/wp-includes/pluggable.php on line 1228

I did the test you guys had and found out that the plugin that's causing me trouble, is this one: (AJAX SEARCH PRO V4.5)
http://codecanyon.net/item/ajax-search-pro-for-wordpress-live-search-plugin/3357410

*****

I've also noticed that this error specifically occurs when I use the [app_confirmation] shortcode. Surprisingly however is that the site can still function if I click preview instead of update.
I'm using Divi and the specific address I need help with is http://koalatutor.ca/real-tutor/
I've also enabled support access just so that you're able to fix this quicker.

Please if you can resolve this issue as soon as you can, I'm in a bit of a hurry. Please and thank you.