Hi all, thanks for your comments
Yes, I created several root categories and subcategories to place some products there. I was following Magento manual to be as sure as possible.
maybe there must be just one root and all the others as subcategories, is that right?
in this case products must be asigned to subcategories instead root categories?
I tried both flush cache and disable it but not working.
Guillermo, I´ll send an email to support.