My guess is that the button hit-check is not inside _any_ function that's been checked... try the code below with and without the "this.onEnterFrame = function () {" and of course the trailing "}" to see the "problem"
Code:
var clicked:Boolean = false;
this.onEnterFrame = function() {
my_button.onPress = function() {
      clicked = true;
	  trace("clicked:" +clicked+ " YEAH");
}

if (!clicked) {
      trace("clicked:" +clicked+ " YEAH");
} 
}