Resizing the size of flash movie

// FUNCTIONS
// a function (applicable to any button holding a movieclip circle_mc) to enlarge circle_mc
function btnRollOver() {
this.circle_mc._xscale = 120;
this.circle_mc._yscale = 120;
}

// a function to return mc to its original size
function btnRollOut() {
this.circle_mc._xscale = 100;
this.circle_mc._yscale = 100;
}

// MOVIE SETUP
// set up event handlers for on stage elements
start_mc.onRelease = floatBubble;

start_mc.onRollOver = btnRollOver;
start_mc.onRollOut = btnRollOut;

pop_mc.onRollOver = btnRollOver;
pop_mc.onRollOut = btnRollOut;