Another problem is that, sometimes users don't get activation links immediately. Today most of users didn't get activation links at all. I decreased the security level from 3 to 2. But it didn't help.
Is there any secret?
You have unpublish the price field if you don't need it, or just remove the title field to be displayed in the option.
About activation, this is not linked to adsmanager but to joomla :)