Thank you for your answer.

I think I can be almost 100% sure, that my requires are done in right order. Because if required files has extension .inc everything works fine. But when I change this extension to .php I get error message. Also the code should be ok, because everything worked ok before changing to .php extension.

Right now I also found this - i tried to add

AddType application/x-httpd-php .inc to my mod_php.conf

so I can leave my classess with .inc and noone can read them as text files. After done so, I get the error message also for .inc files. Strange, isn't it?)

last info: - if I copy my classes directly into main php code, everything works fine...

editProblem solved. I don't know why, but it looks like the problem was in the absolute path.

If I use require_once "http://xxxx.xxx.xxx/SVV/class/databaze.inc" everything works.
If I use require_once "http://xxxx.xxx.xxx/SVV/class/databaze.php" problem occures.
If I use require_once "./class/databaze.php" everything works fine.

If this makes sence I don't want to be sober)