Login with Facebook not working on iOS 7 - code: "-1"

Titanium SDK: 3.1.2.GA Platform & version: iOS 7 Device: iPhone 4s

When the user clicks on the "Login with Facebook" button, I receive:

bubbles = 1;
cancelBubble = 0;
cancelled = 0;
code = "-1";
source = "[object FacebookModule]";
success = 0;
type = login;

on the listener "fb.addEventListener("login", function(e) { ... });".

Can you help me?

Thanks, Michele