Inducing a bluff

[PokerBob]

[ QUOTE ]
Commerce 40/80. Game is playing very very tight and it's not that great, but we're about to break (and unbeknownst to me I'm about to move to an awesome game for the last 2 hours of the night).

Folded to me in the CO, I open AQ. SB calls, BB folds.

Flop 855. Check, I bet, he calls.
Turn A. He checks, I check?

(Plan is for him to bet the river and I raise any card that isn't an 8, T, or J.)

[/ QUOTE ]

If you don't think he has anything, why raise the river? If you think he has a 5, why raise the river? If you think he has an ace, why not bet the turn?