Alerts are not launched

Hello ,

I have some problem with alert triggering.

I created this sample alert :

In trigger action, I add "Send a mail". When I do a test, it's working and I am receiving a mail.... but when a node's cpu goes > 95%, no alert is triggered, so no mail.

Alert is active. To be sure, I deactivated and activated again but nothing was coming into my mailbox.

Anything I missed ?

I should receive a mail.

Regards