I'm not looking for hand analysis on this as I already know I should have bet earlier but I don't understand why a $16 pot did not get any rake taken out. I mean I'm happy it didn't, I just don't understand why.

PokerStars 2/4 Hold'em (4 handed)

Preflop: Hero is SB with , .
2 folds, Hero raises, BB calls.

Flop: (4 SB) , , (2 players)
Hero checks, BB checks.

Turn: (2 BB) (2 players)
Hero checks, BB checks.

River: (2 BB) (2 players)
Hero bets, BB calls.

Final Pot: 4 BB

Results in white below:
BB has 2s Ks (one pair, queens).
Hero has 9s Ac (two pair, queens and nines).
Outcome: Hero wins 4 BB.

rake doesnt hit in party shorthanded limit at 2/4 till $20.

Rake doesnt hit party 2/4 until $20 period, which is why it can be juicier at times as there are a lot less bonus whores there (though party is lacking in the bonus department right now)

same for both sites