Right access in /files/logs

Hello,

I'm going to install project'or on Linux server for deployement in my compagny
I have an error when I launch application see above :
"Le répertoire de log '../files/logs' est vérrouillé. Impossible d'écrire les logs."

If a give access to ./files/logs in R/W for all user by chmod 777 logs

I have a new error without any more information :
ERROR : Une erreur est survenue le 2012-05-16 à 18:36:38

does anybody can help me? (i'm not an expert in PHP/HTTP/SQL management

For information i'm using Debian distrib, apache server, mysql and PHP5

Thx for your help

Thierry,

Now it work, I found my error :
I have inport the Window version to Linux, and the log file was created with read only accès and with the same date of linux's date transfert. Then the software can't write in this file coming from windows world.

Today with new log file the system works fine

Thx
Thierry,