Hi
On a Joomla 2.5.28 + K2 2.6.9 site, the comment form doesn't appears. when I enable the comments for the registered users.
It appears only for the super-user.

If I enable it for any visitors, it works .... but I get a lot of spams.

???

Hello,

You need to make sure that the checks in the item.php file are performed correctly. !$this->user->guest should be used instead of looking for a specific user group.