Although this is fine in SP, it won't work in COOP, for possibly two reasons:
- I assume the humvee driver is an AI not in a player group, so he will exist on the dedicated server, but there is no player on the server. Thus, on the machine that is actually commanding the driver (the server), the value of player is not useful (well, in fact it is objNull).
- If the game is in "BIRD" mode (the default, where you become a seagull on death) then that player is no longer in the group with the living members (you stay in the group in any sort of respawn mode though). Well, actually, this isn't actually important, since the first point is the one that stops things working at all before this one becomes relevant!
I didn't consider MP issues originally, since you posted this in the general, not the multiplayer, forum. All you need to overcome this is to put "group1 = group this;" in every init in the group (you can't just put it in one person's init, since they might not be being played) and use group1 instead of group player, which was the other example I gave.