Hi again, 1st i want to say thank you for your help, but in my case, the problem was another and i want to share it with all the community.
My problem was solved when i started a new proyect and selected United States to locate my Realtime Database. That’s all !!!
All the times i started a new proyect to try to solve the same issue, i selected Belgium (i’m in Spain) like my location for the database.
I don’t remember where i read that solution (appinventor forums i think), but it worked for me, so Thanks to all community that always are there to give some helps and tips.
Regards from Spain!!
Un saludo a tod@s.