New user question about setting up triggers to different scenes then back again

I have created the main content in one scene, the placed practice questions into different scenes.  I clicked on the next button trigger from the main content scene to the first slide in one of the practice question scenes. When I adjust the trigger (Jump to "next slide"  and select the new slide to jump to), then try to preview it before publishing, I get the message at first that I couldn't preview it (I get the message: "the slide target of this link is not available in this preview").  I'm not sure what I'm doing incorrectly. Any ideas? I've attached the project in case that will help. Specifically, slide 1.5 is to jump to slide 2.1 to slide 2.3; 2.3 is to jump to slide 1.6. Slide 1.7 is to jump to 3.1, etc.  Thank you for any feedback you might be able to provide.  Elizabeth