Problems converting AS2 to AS3 (Making Trails)

programming flash
1

Any idea where I’m going wrong? Not quite sure how to dynamically create functions in AS3. Should I just create a trail class, instead of having this in the class of the moving object?

1120: Access of undefined property trailFunction.

// My attempt

            //Create trail
            var Trail = new MovieClip();
            Trail.name = this.name + "Trail" + tC;
            ++tC;
            Trail.moveTo(x-xV, y-yV);
            Trail.lineStyle(3, 0xFFFFFF, 100, false, "none", "none");
            Trail.lineTo(x, y);

            Trail.trailControl = new Timer(50);
            Trail.trailControl.addEventListener(TimerEvent.TIMER, trailFunction);
            Trail.trailControl.start();
            Trail.trailFunction = function() {
            alpha -= .1;
            if (this._alpha <= .1) {
            Trail.trailControl.stop();
            Trail.trailControl.removeEventListener(TimerEvent.TIMER, trailFunction);
            }
            };
            parent.addChild(Trail);



//Old AS2 Script
this.Trail = Trails.createEmptyMovieClip("Trail"+_root.trailDepth, _root.trailDepth);
            _root.trailDepth++;
            if (_root.trailDepth>=16999) {
                _root.trailDepth = 15010;
            }
            this.Trail.moveTo(this._x-xvel, this._y-yvel);
            this.Trail.lineStyle(3, 0xFFFFFF, 100, false, "none", "none");
            this.Trail.lineTo(this._x, this._y);
            this.Trail.fadeSpeed = trailFadeRate;
            this.Trail.onEnterFrame = function() {
                this._x += _root.scrollVel;
                this._alpha -= this.fadeSpeed;
                if (this._alpha<=0) {
                    removeMovieClip(this);
                }
            };
        }