In order to receive text messages on your phone, push notifications have to be enabled.
To check and/or allow push notifications, please do the following
1) Tap the App drawer on your home screen
2) Tap Settings
3) Tap Apps or App Manager (2)
4) Scroll down and tap AddaLine
5) Tap Notifications
6) Make sure "Block all" is unchecked. The other settings you can customize to your liking.
7) Restart your device to make sure it works.
You will now be able to receive push notifications and incoming text messages.