[levAA]

You made two errors in this hand:

1.) not shoving preflop - you raised, got reraised - now you should push with KK - this is standard

2.) not being able to lay down KK when an ace flops. You raise get reraised, an ace flops and villain checks. I think he has hit that flop in more than 90%. By not pushing preflop you have an awful potsize to play now. I think at best you will be up against QQ or JJ. Pushing is wrong here imo. The problem is with any bet you commit too much of your stack. I'd either check behind and fold on the turn or make a c-bet and fold to a push. Both lines suck. But the mistake was preflop imo.