11/13/2014
I see a friend on the roster but cannot join their game.
If you cannot join a game with another player you see on the roster, this may be a result of you and the other player not having the same version of Destiny. To avoid this, be sure both you and the other player have the most up-to-date version Destiny installed.
If you're not sure if you have the latest version of Destiny, restarting the game should apply the latest patch and install the latest version of the game.