Button1_btn On A Frame In The Beginning Of This Animation?

I have button1_btn on a frame in the beginning of this animation, and on that frame I script it:
 
button1_btn.addEventListener(MouseEvent.CLICK, showimage1);
function showimage1(event:MouseEvent):void {
gotoAndPlay("image1");
}

I also have other buttons that eventually take a different frame where that button isn't on.So I add it to the stage in that frame and assume it will gotoAndPlay("image1") again when clicked, but when I test the movie, and click it on the later frame, nothing happens.I tried maybe adding the original script to that frame as well, but then I test and it says I have duplicated script and doesn't work.Why does the original script work for that button, no matter where and when it shows up?It's the same button essentially, no?