Can not connect to Facebook.

Whenever I press the integrated 'link Facebook' button, a message of 'Could not log using Facebook at this moment. Please try again later.'

I've tried deleting the game, logging into Facebook via safari, Google chrome, even the app itself. It's been a few days since this problem occurred, even my brother managed to connect to Facebook, yet I can't.

Edit: I just tried playing the game, whenever I click on a monster, I can't level it up, the tab doesn't display.