If both you and your friends are connected to LOTB through Facebook but are unable to see each other in the game, it’s likely because of your Facebook settings.
To resolve this, both you and your friends should do the following:
1. Log-in to your Facebook account as usual (not from the app)
2. Click on "Settings"
3. Click on "Apps and Websites"
4. Check the "Backgammon Lord Of The Board" box
5. Click on "View and Edit"
6. Make sure that "Friends List" is enabled
7. If this setting was not enabled, enable it and click "Save"