Can't get Key.isDown to work

programming flash
1

I’m using a movie clip as a button on the main time line and need the user to use the keyboard to control the movie.

I’m using

this.onEnterFrame = function(){

if (Key.isDown( 49 )){

_root.gotoAndPlay(3);

}
}

But thats not working, can anyone tell me where I’m going wrong.

I’m using AS2.0

cheers