Helium Scraper

I have added extract and navigate to the action tree. However, I am not able to add child extract and navigate under the first added extract and navigate. New action button does not work when I try to add child extract and navigete.
the picture located at the bottom; the extracts and navigates have been edded under repeat 1 time. But, I want to add extracts and navigates under each other like the picture located at the above.

I think you meant to use a Navigate Each action instead of a Navigate one. Navigate Each will run its child nodes for every navigated item. Navigate will just navigate one link and then the next action will execute. So it doesn't really make sense for this action to support having child nodes.