Hi Dave, welcome to the forum - you don't need to SHOUT as we're not all deaf :-)
The alerts will only trigger when the aircraft first appears, so if you already have these aircraft types showing when you set the alert, they won't generate an alarm - but the next B772 will etc.
Have you got the "Activate Alerts for Network flights" ticked? If not, you will only get alerts for the aircraft you pick up from your antenna.
Remember that you can use wild cards in the alert box - B77* will pick up all B777 types and the same for B73* and A34*. I'm not sure why you need an email alert for all these - but generally, either the email alert works (almost everybody) or it doesn't work at all (a few people).
Regards
Allocator