How do I IGNORE CPU alerts for specific hosts?

I have alerts setup for a specific page in Xymon. There are certain host that go Red and green throughout the day whichs sends out alerts. The Wintel team is aware of the issue. I would like to create an expection for these specific hosts not to send out notification.

I tried this based on documention i found but its not working.

IGNORE HOST=$CPU_EXCEPTION SERVICE=cpu $NOTIFICATION_GROUP

Thanks