You can try to fix your problem by doing this:
1. Make sure you have a stable internet connection.
2. Make sure your game is connected to Facebook.
If the problem persists, try the following:
1. Open the game settings and tap Facebook – Connected to disconnect from it.
2. Restart your device and reenter the game.
3. Reconnect your game to Facebook. You should now be able to get lives from your friends.