Button only works once！ I NEED HELP~

Hi, I'm working on my project and it is basically a animated storybook. I have like 20+ scenes and in each of the scene there is a next and previous button to jump from scene to scene, but now I am facing a problem on my next and previous button which is when I perform test on FLV the button only works once. For example: I'm now in Scene 1 and I clicked on the next button to jump to the scene two, and when I clicked on the previous button to go back to Scene 1 the button is not working anymore. Can anyone please provide me a solution about my problem? I really appreciate that! >.<

This is my ActionScript Code for my button in every scenes:-

import flash.events.MouseEvent;

stop();

next_btn1.addEventListener(MouseEvent.CLICK, nextpage2);

function nextpage2(event:MouseEvent):void

{

          gotoAndStop(26);

}

PrvButton1.addEventListener(MouseEvent.CLICK, prvpage_main);

function prvpage_main(event:MouseEvent):void

{

          gotoAndStop(1);

}