cannot enable automatic course backups

Hi All, We are running Moodle2.2.7+ (Build: 20130118) and are experiencing problems activating automatic course backups.

I go into Site administration

• /►Courses
• /►Backups
• /►Automated backup setup

When i change the first box named "active" to enabled and click save changes, the change is not saved, it keeps reading "disabled". Same result if I set to "manual".

I run admin/cron.php and it tells me that auto backups are inactive.  I have noted that the following is added to config.php

$CFG->disablescheduledbackups = true;
$CFG->forced_plugin_settings = array('backup' => array ('backup_auto_active' => 0));
if (file_exists("$CFG->dirroot/lib/setup.php"))  {       // Do not edit
    include_once("$CFG->dirroot/lib/setup.php");
}

I have tried removing  the line "$CFG->disablescheduledbackups = true;" but I still cannot enable autobackups as active.

Any help would be appreciated

Thanks in advance