[Plugin: ShowTime Slideshow] page did not run after installation

I tested the plugin in a test site, it worked fine. Installed it in production and I got the following message (or similar) for every picture I uploaded.

Warning: Cannot modify header information – headers already sent by (output started at /home/friends2/public_html/wp-includes/functions.php:3551) in /home/friends2/public_html/wp-admin/async-upload.php on line 26

Is there anything I can do to make it work? It works just fine on the test site and they are supposed to be mirrors.

Thank you,

yorksett

https://www.ads-software.com/extend/plugins/showtime-slideshow/