Why won't the facebook messenger app on my iphone give me notifications?

I just got the iPhone 5s today and I use the facebook messenger app to talk to everyone I know. I downloaded the app onto my new phone and i set the notifications to on and everything is where its supposed to be. The phone vibrates when i get a message only when the messenger app is open. Not when its closed or if the phone is locked. I used to have the iPhone 4s and it worked fine on that phone. I compared what the notifications settings were on my old phone to my new phone and they're all identical but i won't get notifications from facebook messenger. How do i fix this? Please help before I punch someone in the face out of frustration.

Go to "Settings" on your iPhone and then go to "Notifications". Then, find the "Not In Notification Center" column and find your app (Facebook Messenger). Then click on that and swipe the "off" to "on"

You can uninstall and then install again… It can work.