Warning: require_once(zp-core/zp-extensions/image_album_statistics.php) [function.require-once]: failed to open stream: No such file or directory in /web/htdocs/www.---.it/home/galleria/themes/zpskeleton/functions.php on line 57

Fatal error: require_once() [function.require]: Failed opening required 'zp-core/zp-extensions/image_album_statistics.php' (include_path='.:/php5/lib/php/') in /web/htdocs/www.---.it/home/galleria/themes/zpskeleton/functions.php on line 57

I added the name of the 3rd party theme to the topic title so its author may be able to respond.

Just for the record, the problem would seem to be that the theme has not fully qualified the path to image_album_statistics.php and then is trying to load it within a subfolder so the file search works within that subfolder and naturally does not find the plugin.

yes, true, but why this happens only sometimes and not always?
For example, if you reload the page after 5-6 times without any changes, the error is shown

@sbillard Speaking of errors, there is an obvious one in the Forum Rules:

"please make your posts explicit so we can see that you have real interesst."

Got the point, though.

I replace manually :

if ($zpskel_strip == 'latest') require_once (ZENFOLDER."/zp-extensions/image_album_statistics.php");

with:

if ($zpskel_strip == 'latest') require_once ("/web/htdocs/www.----.it/home/galleria/zp-core/zp-extensions/image_album_statistics.php");

at line 57

and now work fine

Glad you got it working. Just FYI, there is a define for the server path that you could use as well--SERVERPATH

It might not happen always if some other place properly loaded the script.