Query alert is in 'alerting' state for ever


I make a dashborad, from a prometheus datasource. I make it with a simple query:


When I set an alert and the conditions are met, the alert changes to an “alert” state forever. Even if the condition is no longer fulfilled, this state remains constant. How can I configure this?

Here is the situation, the conditions off and the dashboard its in alerting state:

My alert config:

Thanks a lot!