Issue with uploaded image

Please, can anybody help me with this? When I upload image, everythig goes OK, I cannot see it on gallery. Well I see it, but thumbnail is missing and there is this error:

Warning: Division by zero in /data/web/virtuals/49772/virtual/www/wp-content/plugins/nextgen-gallery/products/photocrati_nextgen/modules/ngglegacy/lib/gd.thumbnail.inc.php on line 293

What is it? How can I fix it? Please hurry, my client is angry :/

https://www.ads-software.com/plugins/nextgen-gallery/