Actually, Jindo, you CAN join online games (I've even seen you online... ), but only those of the same version as you. Many games are greyed out because their hosts are running 1.23, while you have 1.24. Unfortunately, the majority of games are hosted with 1.23, so it's best if you install 1.23 and TSF (1.24) separately (if you bought TSF, you should receive a free copy of JJ2 1.21, which can then be upgraded with a patch to 1.23).