Scaling, alpha, position issues

1

I tried using this code because I need some mc to scale, others to fade, and others to move; but it won’t work. It only allows the last function to work (in this case alpha).

MovieClip.prototype.easeScale = function(scaSpeed, mcH, mcW) {
this.onEnterFrame = function() {
this._height += (mcH-this._height)/scaSpeed;
this._width += (mcW-this._width)/scaSpeed;
};
};
MovieClip.prototype.easePosition = function(posSpeed, mcX, mcY) {
this.onEnterFrame = function() {
this._x += (mcX-this._x)/posSpeed;
this._y += (mcY-this._y)/posSpeed;
};
};
MovieClip.prototype.easeAlpha = function(alpSpeed, mcA) {
this.onEnterFrame = function() {
this._alpha += (mcA-this._alpha)/alpSpeed;
};
};
box_mc.onRelease = function() {
box_mc.easeScale(8, 100, 10);
box_mc.easePosition(8, 400, 300);
box_mc.easeAlpha(8, 60);
};