I'm sorry that this has been happening to you. I am going to give you a short list of stuff to try out on your device and we will see if that solves the problem.
1. Try uninstalling and reinstalling the game
2. Try rebooting your device
3. Make sure that you have the Facebook application on your device and it is signed into that account.
4.Sign out and back into your Facebook application.
Let us know if you are still having this issue.