not displaying thumbnails

Hi, as subject thumbnails are not properly shown
Everything is correct, title, link etc. but thumbnails aren't. Another strange things is that I use the same modules, but with articles from Easyblog, and thumbnails from it are shown correctly.
I don't know if it is useful and it is related, but there are some errors in error logs

client denied by server configuration: /var/www/html/modules/mod_news_pro_gk5/cache/.html.immagini.informarsi.ambiente.ispra2015nsp-509.jpg, referer:
and of course all the images not shown

other errors
Undefined property: stdClass::$content in /var/www/html/templates/gk_news2/lib/menu/GKHandheld.php on line 123
Undefined property: stdClass::$content in /var/www/html/templates/gk_news2/lib/menu/GKHandheld.php on line 176

Could you please provide me with a URL to your website, either here or via PM (click the “Private Message” text underneath my avatar) so that I may analyze it? It is a lot easier for us to diagnose issues when we have a live site to examine.

sure. Unfortunately today I'm changing server, so it's not accessible. At soon it will be changed I write again. Thx.

solved!
It was an apache configuration for which didn't show resources starting with "ht" or ".ht"
so images, stored as html.xxxxxxxxxxx.jpg couldn't show

Thx

Hi

Thank You for this answer. I have one more problem similar to Yours, so I'll ask user to check that as well