Notification problems – Messenger Review

When I receive a message on my messenger app for Facebook, I NEVER receive the notification regardless if I keep deleting and re-downloading the app! I never notice I get a message until I go on the app myself after hours without getting notified of anything. You guys really need to fix this problem cause it's really annoying! FIX ASAP PLEASE!!
Review by Suhaila_xo on Messenger.