Code doesnt even work

The game is great but it gets 4 stars because the new player/friend referral system is broken. My code didnt work for my friend and my brothers didnt work for me. My brother and I are friends on Facebook and yet we dont get workers from each other, and it doesnt even show us as friends. Other than this, it is an excellent game.

Referall System Broken about Motor World: Car Factory, v1.7520