5/10 AK multiway 4-bet

[photojake]

Full Tilt Poker 5/10 Hold'em (6 handed)

Preflop: Hero is MP with A, K.
1 fold, Hero raises, CO calls, Button calls, BB raises, Hero caps, CO calls, Button calls, BB calls.

Flop: (16.5 SB) 6 [img]/images/graemlins/heart.gif[/img], 5 [img]/images/graemlins/club.gif[/img], 4 [img]/images/graemlins/diamond.gif[/img] (4 players)
BB bets, Hero calls, CO calls, Button calls.

Turn: (10.25 BB) 7 [img]/images/graemlins/club.gif[/img] (4 players)
BB checks, Hero checks, CO bets, Button calls, BB folds, Hero calls.

River: (13.25 BB) A [img]/images/graemlins/heart.gif[/img] (3 players)
Hero checks, CO bets, Button calls, Hero calls

Comments?

Should I have raised on the flop? Is this a good line? What would be a better line of action?