Setting rollOvers in a for loop

so this seems like it should work, i’m probably missing something but i just cant see it.
i’ve got some buttons on the stage named btn1_mc through btn8_mc. what i wanted to do was use a for loop for there rollover functions so make the code cleaner. what i got so far is


stop;
var i:Number = 1
for (i=1; i<=8; i++){
var __btn = "btn"+i+"_mc"
trace(__btn)
__btn.onRollOver=function(){
trace("rollover")
}
}

the first trace shows btn1_mc through btn8_mc. so thats working but i just cant get the rollover to work. im prolly missing somethign simple but i just cant see it now.
thanks in advance