Should I be raising this flop?

[AlcateL]

This is actually quite a general question, but should I be raising the pre flop raiser on this flop? Or shou;d I be seeing a turn hoping he'll bluff more chips away at me (assuming he's bluffing) or do I raise here to find out where I am? I have few reads on the opponent as I've only been sat for 20 minutes on the table, however he is certainly more of a LAG than anything else.

As this hand panned out he checked to me on the turn and I bet he folded, as expected, would I Be better off raising this flop thus finding out where I am as well as betting him off his overcards/draws.

Party Poker No-Limit Hold'em, $ BB (6 max, 6 handed) FTR converter on zerodivide.cx

CO ($98.55)
Hero ($206.15)
SB ($25.17)
BB ($121.57)
UTG ($63.30)
MP ($46.23)

Preflop: Hero is Button with T[img]/images/graemlins/diamond.gif[/img], J[img]/images/graemlins/diamond.gif[/img]. SB posts a blind of $0.50.
<font color="#666666">2 folds</font>, <font color="#CC3333">CO raises to $4</font>, Hero calls $4, <font color="#666666">1 fold</font>, BB calls $3.

Flop: ($12.50) J[img]/images/graemlins/club.gif[/img], 9[img]/images/graemlins/spade.gif[/img], 4[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(3 players)</font>
BB checks, <font color="#CC3333">CO bets $11</font>, Hero calls $11, BB folds.

Turn: ($34.50) 8[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(2 players)</font>
CO checks, <font color="#CC3333">Hero bets $20</font>, CO folds.

Final Pot: $54.50

[gol4pro]

100% opponent dependent. Against LAG's, raise the flop with some randomness to keep them guessing. Against TAGs, RCK's, I don't like a flop raise at all.