Unable to update configuration file

Hello,

I can't change configuration within parameters.php.

For example : chaging name of instance.
Via Global Parameters, i change the field and save, PorjeQtOr say "OK" and nothing in log.
I go to User's Parameters so back to Global Parameters, value is old one (no change take effect).
If i change a value stored in database, no problem.

If check rights for parameters.php : -rw-rw-r-- 1 apache:apache parameters.php
No selinux enforcement active.
No error report by ProjeQtOr nor php.

If i change value directly in parameters.php, it works (so i use the right parameters.php file).

I try others values stored in parameters.php (ldap, currency,...) and i get the same...
Any idea ?

Ok but why i can't change values in parameters files via ProjeQtOr ?
No error message, no error logged but nothing is changed...