Why doesnt this work?

1 

this.createEmptyMovieClip("img_mc", this.getNextHighestDepth());
img_mc.attachMovie("a", "a_mc");

function go() {
	for (i=0; i>=100; i++) {
		duplicateMovieClip(img_mc, "newImg_mc", this.getNextHighestDepth());
		newImg_mc._x = random(Stage.width);
		newImg_mc._y = random(Stage.height);
	}
}

go();

I have a mc in the library that is a black circle with a linkage identifier “a”