private function incno() : void {
   setid(cameraNo+1);
   }
   private function decno() : void {
   setid(cameraNo-1);
   }
   private function setid(n:Number = 0) : void {
     cameraNo = n;
     if (n > 0) cameraId = "" + (n-1);
     else cameraId = "0";
     cameralabel.text = "" + n;
   }