Baffled: fade in fade out function

1

this code is so not working, am i missing something very subtle?
all it does is fade in and out an object when you roll over it.

_root.block2.tn.onRollOver= function(){
glow = true
}
_root.block2.tn.onRollOut=function(){
glow = false
}
if(glow == true){
fadein(block2.tn)
}else{
fadeout(block2.tn)
}

function fadein(n){
if (n._alpha<100){
n._alpha +=10
}
}

function fadeout(n){
if(n._alpha>0){
n._alpha -=10
}
}