[AS2] Is confused about a path to a MC

So er... I made a MC, and called it 'waterdrop' on the stage. Now I have a MC that's linkage name is 'snow', and within the Waterdrop MC I use attachMovie to add the 'snow' to the scene. Simple.

However, it all messes up around here:

Code is from Control MC within 'waterdrop' MC

Code:

---

onClipEvent(enterFrame) {
        var i2 = _root.getNextHighestDepth();
        attachMovie("snow","snow"+i2,i2);
        with (_root.waterdrop["snow"+i2]) {
                _x = 425+40-80*Math.random();
                _y = 90+45-90*Math.random();
                _rotation = 60*Math.random();
                _xscale = _yscale = 30*Math.random();
                _alpha = 100;
        }
        _root.waterdrop["snow"+i2].onEnterFrame = function() {
                with (this) {
                        _x += _xscale/13;
                        _y -= _yscale/30;
                        _alpha -= 2;
                        if (_x>896 || _y>672 || _alpha<0) {
                                this.removeMovieClip();
                        }
                }
        }
        updateAfterEvent();
}

---

This piece of code works great if it's started by _root.onEnterFrame = function() and use the _root["snow"+i2] path to locate, but if I adapt it to above code, Flash Player tells me that it can't find the specified object for the With(){...}

Can anyone correct this code for me?

Oh, notes:
It basically attaches the clip at a random position near the (425,90), and then let it float sideways on a 1:3 gradient, gradually losing alpha and then getting removed if it drifts out of sight OR if it is transparent.

PHP Code:

---

onClipEvent (load){i3 = _parent.getNextHighestDepth();}
onClipEvent (mouseMove) {
    i3 ++ 
//weird, because trace(i3) actually returns a increasing number.
    attachMovie("snow","snow"+i3,i3);
    with ("_level"+i3["snow"+i3]) { //working
        _x = 0+40-80*Math.random();
        _y = 0+45-90*Math.random();
        _rotation = 60*Math.random();
        _xscale = _yscale=30*Math.random();
        _alpha = 100;
    }
    trace ("_level"+i3["snow"+i3].getDepth()); //output: _levelundefined
    this.onEnterFrame = function() { //working
        with (this) {
            _x += _xscale/13;
            _y -= _yscale/30;
            _alpha -= 2;
            if (_x>896 || _y>672 || _alpha<0) {
                this.removeMovieClip();
            }
        }
    };
    updateAfterEvent();
} 


---

I made it work by accident, but now the ["snow"+i3] is on _levelundefined according to the trace().
but didn't I attach the clip to the depth i3?