Can someone please tell me when you are ahead the river cant be blank?

I was playing in a $1.00 + .20 sit and go on Pokerstars. I had to steal pots when I could because I was drawing so cold it wasnt even funny anymore. This is the final hand from this sit and go. I was delt Ac As with 725 in chips left. I was in late position and decided to only smooth call the big blind. BIG MISTAKE.. or was it?

Only 3 of us saw the Flop. The BB, the Button and myself. Pot Size 175

Flop: 5s Qs Ks

A scary looking for for someone with Aces however with top pair and top spade I felt like I was ahead in this hand. The BB checked so I bet 100. The button quickly raised me all-in. After thinking this over I decided that I was ahead so I called.

The button turned over 6s Qh I was at this point I am an 85% favorite.

Turn: 4d

I was feeling very good at this point. My hand was now a 88.7% favorite to win. He needed to pull a 2 outer on me to win this hand. I had him on Spades.

Flop: Qd

Unbelievable! And my tournament is over. Why can't the river ever be a blank?

PokerStars Game #7101721852: Tournament #36289860, $1.00+$0.20 Hold'em No Limit - Level III (25/50) - 2006/11/20 - 12:56:03 (ET)
Table '36289860 5' 9-max Seat #6 is the button
Seat 1: Hellaw8ts (1180 in chips) is sitting out
Seat 2: fireman24 (1870 in chips) is sitting out
Seat 4: bobbyray912 (1065 in chips)
Seat 5: crezzy8 (2610 in chips)
Seat 6: Sane_Robbins (870 in chips)
Seat 7: DzemAs (1245 in chips)
Seat 8: icyTy (5045 in chips)
Seat 9: yeknodami (725 in chips)
DzemAs: posts small blind 25
icyTy: posts big blind 50
*** HOLE CARDS ***
Dealt to yeknodami [Ac As]
yeknodami: calls 50
Hellaw8ts: folds
fireman24: folds
bobbyray912: folds
crezzy8: folds
Sane_Robbins: calls 50
DzemAs: folds
icyTy: checks
*** FLOP *** [5s Qs Ks]
fireman24 has returned
icyTy: checks
yeknodami: bets 100
Sane_Robbins: raises 720 to 820 and is all-in
icyTy: folds
yeknodami: calls 575 and is all-in
*** TURN *** [5s Qs Ks] [4d]
*** RIVER *** [5s Qs Ks 4d] [Qd]
*** SHOW DOWN ***
yeknodami: shows [Ac As] (two pair, Aces and Queens)
Sane_Robbins: shows [6s Qh] (three of a kind, Queens)
Sane_Robbins collected 1525 from pot
*** SUMMARY ***
Total pot 1525 | Rake 0
Board [5s Qs Ks 4d Qd]
Seat 1: Hellaw8ts folded before Flop (didn't bet)
Seat 2: fireman24 folded before Flop (didn't bet)
Seat 4: bobbyray912 folded before Flop (didn't bet)
Seat 5: crezzy8 folded before Flop (didn't bet)
Seat 6: Sane_Robbins (button) showed [6s Qh] and won (1525) with three of a kind, Queens
Seat 7: DzemAs (small blind) folded before Flop
Seat 8: icyTy (big blind) folded on the Flop
Seat 9: yeknodami showed [Ac As] and lost with two pair, Aces and Queens