Frame advance by touch screen pressed and dragged.

The compiler does not run because of an error, a conflict according to the compiler:

"There is a conflict with the inherited definition flash.play: Sprite: startDrag in namespace public"

Would you help me?

var tret:int = 1;
var startDrag: int;
your_btn.addEventListener(MouseEvent.MOUSE_DOWN, downF);
function downF(e:MouseEvent) : void { 
  startDrag = e.stageX;
  stage.addEventListener(MouseEvent.MOUSE_UP, upF);
}
function upF(e:MouseEvent) : void {
  if(e.stageX > startDrag + tret) {
  this.prevFrame();
  } else if(e.stageX < startDrag - tret) {
  this.nextFrame();
  }
}