Proper turn play with aces and facing a check/raise?

[hammerva]

This probably the 4th or 5th hand in another poor limit session:

Full Tilt Poker
Limit Holdem Ring game
Limit: $0.50/$1
9 players
Converter

Stack sizes:
UTG: $20.55
UTG+1: $9
MP1: $9.40
MP2: $0.95
MP3: $41.50
CO: $23
Hero: $18.70
SB: $19.90
BB: $19

Pre-flop: (9 players) Hero is Button with A[img]/images/graemlins/club.gif[/img] A[img]/images/graemlins/diamond.gif[/img]
UTG calls, 4 folds, CO calls, <font color="#cc0000">Hero raises</font>, SB calls, BB calls, UTG calls, CO calls.

Flop: K[img]/images/graemlins/heart.gif[/img] 2[img]/images/graemlins/diamond.gif[/img] 3[img]/images/graemlins/diamond.gif[/img] (10SB, 5 players)
SB checks, BB checks, UTG checks, <font color="#cc0000">CO bets</font>, <font color="#cc0000">Hero raises</font>, 3 folds, CO calls.

Turn: 6[img]/images/graemlins/heart.gif[/img] (7BB, 2 players)
CO checks, <font color="#cc0000">Hero bets</font>, <font color="#cc0000">CO raises</font>, Hero ???

I guess I should assume that if someone checks on the flop and then magically check/raises on the turn that the 6 really helped him. I guess the question is whether this is a crying call situation or a simple turn fold?