A9o shortstack ITM with one raiser and a flat call

[gcaash]

PokerStars Tournament, Big Blind is t200 with t25 antes (3 handed) Converter on pregopoker.com

Button (t6031)
SB (t5605)
Hero (t1864)

Preflop: Hero is in BB with 9[img]/images/graemlins/spade.gif[/img] A[img]/images/graemlins/heart.gif[/img]
<font color="red">Button raises to t400</font>, SB calls t300, <font color="gray">Hero folds</font>


sngwiz sas that its correct , but i dont understand why , they are calling me with lots of weaker hands .
if someone could explain to me why this is a fold it would be nice .