Error message on top of dispaly settings page

I am getting this message on top of the Display settings page :

Strict Standards: call_user_func_array() expects parameter 1 to be a valid callback, non-static method PT_Content_Views_Admin::display_sub_page_add() should not be called statically in /home4/ab20882/public_html/kths/wp-includes/plugin.php on line 496

This is an amazing plugin, I hope I get this problem solved, Thank you!!!

https://www.ads-software.com/plugins/content-views-query-and-display-post-page/