Virtuemart 3.8.8: how to show the products of the subcategories

[panta7]

Hello to all,
I have a tree like this:
- Category
- SubCategory
--- SubSubCategory
the products are all assigned to SubSubCategory.
I would like a menu item "Virtuemart single category" in which I assign "Category" to show me all products of all subcategories. What happens instead: that I don't see anything. But if I give to the menu voice the "SubCategory" then I see them. It is as if the Virtuemart configuration option "show the products of the sub-categories" stops to show only one sub-level and not all the sub-levels. I await yours, thank you