I can't see what's the problem.
Which core version?
Which protector version?
If you install Protector 3.1.x, set XOOPS_TRUST_PATH.
// XOOPS Trust Path
// Physical path to your XOOPS trusted directory WITHOUT trailing slash
// Example: define('XOOPS_TRUST_PATH', '/path/to/xoops/trusted_directory');
//define('XOOPS_TRUST_PATH', '/var/www/vhosts/foititakos.gr/httpdocs/xoops/xoops_trust_path');
define('XOOPS_TRUST_PATH', '/var/www/vhosts/foititakos.gr/xoops_trust_path');
I recommend this path '/var/www/vhosts/foititakos.gr/xoops_trust_path' for XOOPS_TRUST_PATH.
(Reupload it)