why the function repeat

hello

in this link you can see asample of counting 

http://hebrewgames.org/test/test1.html

when click + or _ it is counting ok

when click NEXT PAGE

when click + or - it is counting not ok it is look like repeating the function.

code:

frame 0:

this.stop();

this.counter=0;

this.plus_bt.addEventListener("click", countUp.bind(this));

function countUp()
{
this.counter= this.counter+1;
this.countTx.text=this.counter;
}

this.minus_bt.addEventListener("click", countDown.bind(this));

function countDown()
{
this.counter= this.counter-1;
if (this.counter<0){this.counter=0}
this.countTx.text=this.counter;
}

this.nextPage_bt.addEventListener("click", nextP.bind(this));

function nextP()
{
this.gotoAndPlay(1);
}

this.prevPage_bt.addEventListener("click", prevP.bind(this));

function prevP()
{
this.gotoAndPlay(0);
}

frame1:

this.stop();