this.stop(); prevents preview working

I have just built a HTML5 Banner using Adobe Animate, and I do wish it to stop looping. A lot of people have complained that this.stop(); isn't working. However for me after I have added this into actions, and press CTRL ENTER to preview the animation -- i just get a blank page. When i remove this.stop(); it works fine. So there is something wrong with this script.

I can't find the setting about combined Sprint files either.

Any ideas what is going on here?

Thanks