Assignment

Recently I upgraded to Moodle 1.7, and since that day the teacher doesn't receive anymore mail notifications when student upload a submission for the assignment.

Other email (ex. backup notif) seems to work correctly.

I checked in code, I think that the problem is that the course is group-separated, but the student is not in a group. In fact, the problem is here (file /mod/assignment/lib.php, line 1379):

if (groupmode($this->course, $this->cm) == SEPARATEGROUPS) { // Separate groups are being used
if ($groups = user_group($this->course->id, $user->id)) { // Try to find groups
$teachers = array();
foreach ($groups as $group) {
$teachers = array_merge($teachers, get_group_teachers($this->course->id, $group->id));
}
} else {
$teachers = get_group_teachers($this->course->id, 0); // Works even if not in group
}
} else {
$teachers = get_course_teachers($this->course->id);
}

No teachers are found... if I set to FALSE the first "if", the mail is sent... Can someone help me? What can I do? I tried with teacher in a group, or in no group.