Prototype and passing parameters question

1

Here’s my code:

frame 1

// quadratic easing out - decelerating to zero velocity
time = 0;
beginX = 100;
changeX = 400;
durationX = 40;
Math.easeOutQuad = function(time, beginX, changeX, durationX) {
    return -c*(t /= d)*(t-2)+b;
};
MovieClip.prototype.animate = function(theClip) {
    theClip.onEnterFrame = function() {
        trace(time);
        if (time<=durationX) {
            this._x = Math.easeOutQuad(time, beginX, changeX, durationX);
        } else {
            this.onEnterFrame = null;
        }
        time++;
    };
};

button

on (release) {
    animate(myMC);
}

I have a movieClip called ‘myMC’. When I click the button I’d like to have the movieClip animate with the easing out effect. Where am I going wrong here?