Thanks for the reply wvxvw! Yeah, it used to work in AS2, but the format it had was:
this.attachMovie("menu button", "menuButton"+i, this.getNextHighestDepth());
but since As3 got rid of attachmovie and getnexthighestdepth, I had to reformat it to it's current incarnation:
var menuButton:MovieClip = new "menu button"();
Did I translate it wrong? I assumed it was correct since I didn't get any errors at runtime. But this output error has me pacing the walls and ceiling!
Thanks for the heads up on the onRelease and Rollout thing, it'll give me a quick distraction before I have to come back to solving this problem again.