little rant, need advice

I'm tired of junk players!

I'm in a $10 buy-in tournament, 25 players signed up for it.

Three rounds (meaning (to me) that the blinds went up three times so far) going by, and I'm sitting happy in "first" place (chip lead)

Ok

I get dealt AA, late position (I think I was next to the button)
I raise 4x the blind, and get one caller.

The flop came with K 2 6
I bet 1/3 of my stack

He calls

turn comes 8

I bet 1/3 again, he calls

river 10

At this point, I'm putting him on chasing flush, but there's no flush in site - so I bet 1/2 my stack, putting the dude all in

cards flip, he's holding K 2 off

~blink~

what'd I do wrong