Not A Bad Beat, I Justed Play The Hand So Bad

[ChoppingAway 0]

Mtt on UB, with 54 players left and an above average stack of 10225 im on the button with A9off, it folded around to the cutoff and he limped for 150, i raise to 600, I like my play so far as the cutoff could have a range of hands from a J-10, any ace rag,Q-10/QJ,K-Q,K-J, he also could have a big hand but based on his play so far i thought that was unlikely. The flop came off Qh Jh 7d, I have continuation bet almost every time,usually picking up the pot, this time when they check to me I check, the turn come Ad, the BB leads out the size of the pot, the cutoff folds, and for some reason I have no idea why, I move in, he thinks until they give him the 15 seconds to act prompt and then calls with AK, river blank. I hate my play if continuation bet the flop i could pick it up, and i should have folded on the turn. your thoughts.