Help with setInterval

Hello,
I am new to using setInterval and I cannot get the clearInterval command to work. I have a panel that is tweening down into the stage about 4 seconds after the movie loads and then I do not want it to happen again. Right now the panel continues to tween in everytime I close it. Right now, the clearInterval is not working.

var down:Boolean;
var currentInterval:Number;
down=false;

function autoDown() {
if (down!=true){
Tweener.addTween(mcMain,{_x:0,_y:30,time:1,transition:“strongEaseOut”});
Tweener.addTween(back_mc,{_blur_blurY:0,_blur_blurY:40, time:1});
mcMain.mcMovie.my_FLVPlybk.play();
down=true;
downOnce=true;
}
}
currentInterval=setInterval(autoDown,2000);
stopInterval=function(){
if (down!=false){
clearInterval(intervalID);
}
}