Quite a rubbish script

I copied this script from a book of mine, it's supposed to make bubbles float upwards, but its manufunctioning again! (total count: 5)

script as follows, I call the bubble snow and i added a invisible mc called control

Code:

---

//well this is the actionscript on "snow"
onClipEvent (load) {
        speed = random(5) + 2;
        tint = random(10) - 5;
}
onClipEvent (enterFrame) {
        this._y = this._y - random(2) - speed;
        this._x = this._x + tint;
        if (this._y > -10) {
                this.removeMovieClip();
        }
}

---

Code:

---

//and this is the actionscript on "control"
onClipEvent (load) {
        i = 0
        num = 5;
}
onClipEvent (enterFrame) {
        for (p=0; p<num; p=p+1) {
                _root.frame.swapDepths(i+num+1) ;
                _root.snow.duplicateMovieClip("snow" + i, i);
                _root.["snow" + i]._y = 930;
                _root.["snow" + i]._x = random(920);
                _root.["snow" + i]._xscale = speed*3;
                _root.["snow" + i]._yscale = _root.["snow" + i]._xscale;
                i = i+1;
        }
}

---

so what in heaven's name is wrong?

not meaning to pester but...