Double check under your Notifications area in the Settings app. Not only do you have to activate notifications for every app (some of which are defaulted to be off), but you can also have the app have no notification, a banner notification or the "old" pop up notification. So, if you've got it set to show no notification in the area for notification style, you won't see a notification, even though you've turned it on.
Huh. That sentence made a lot more sense in my head. But, my point is, notifications is a little more complicated to get it set up correctly. There's more options.
So, all I can say is to check again ... cause I've got no other advice. Sorry.
Marilyn