That is weird!
Have you checked the JavaScript console as described in chapter 2? That is usually the quickest way to figure out what’s going on.
If you’ve checked there and don’t see any errors, please share all of your code as described in the forum welcome post. Either use the Share option in 3DE or copy your code and paste it in here. If you copy & paste, be sure to use the instructions in the forum welcome post.
-Chris