[otrs] priority update notification

Hi, I'm trying to get OTRS send notifications to the ticket owner if the ticket priority has been updated to state 'high' or 'very high' by customers/agents. I played with different settings in the Notifications(event) window, but to no avail. After changing the priority in TicketZoom->Priority by the agent, nothing is sent and I don't see anything like SendAgentNotification in History. Other notifications based on events are being sent perfectly, so the problem is not with the email settings. The only idea I have is that I switched off adding notes as well as other fields in the ViewPriority except selecting the next priority. Maybe the PriorityUpdate notification is triggered only by adding a corresponding note?