Problem with automated backup

Hi,

I don't figure the error, but when I enable the automated backup for the courses in a specified folder, It seems moodle can't figure well the permissions.

I created the folder /backupMoodle and give it 777 as permissions to try to debug the problem:

After that if I enable the automated backup, the following error appears, and I can't figure what is happening. May be php can't go outside /var/www/?

Thank you

Regards