Resize MC when OnRollOver - AS2 Flash8

I´ve been trying to make a very simple thing with AS2 but it seems it´s too much for me. I want to make three MC and when onRollOver I want to scale each one of them to 120% and when onRollOut to go back to 100%.
If I write the entire code it works, but when I try to make a function it doesn`t. I´m a complete newbie with flash so I apollogize for asking for help with this.

Instance Names: foto1, foto2 , foto3

Code: zoomin = function (){
this._xscale=_yscale=120
}
zoomout = function (){
this._xscale=_yscale=100
}
foto1.onRollOver=function(){
zoomin();
}
foto1.onRollOut=function(){
zoomout();
}