Open Source Document Management System | OpenKM

Hi everyone.
I use the following code to fetch documents content:
$content = $OKMDocument->getContent(self::$_auth, $item->document->path, false);
In fact code is not important.
It works perfect but in one case it does not (null).
Document path is valid! I've checked in OpenKM, it exists.
Uuid too.
All other documents are returned OK.
PHP memory_limit is fine.
What can the reason be?
Please, share your suggestions.

Regards, Bogdan

Anyone alive here?

Are you using OpenKM 6.2? Please post a pice of code to reproduce the issue.