Duplicate Movie

programming flash
1

Okay Im attaching a mc from the library, works fine. Then I try to duplicate it and tile horizontally and it doesnt work. What am I doing wrong?

//Set coordinates of holder mc to 0, 0
holder._x = 0;
holder._y = 0;

holder.attachMovie("picx","pic",1);
trace(holder.pic);

holder.onEnterFrame = function(){
  for(i=0;i<3;i++){
    duplicateMovieClip("pic","p"+i, i);
    trace(eval("p"+i));
    with(eval("p"+i)){
      _x = (i/3)*150;
    }
  }
}
delete holder.onEnterFrame;