I get a blank page when I try to access to every user profile URL

I installed the latest version of Profile URL and all of its Jomsocial plugins. I checked that all the plugins were activated. I ordered all the system plugins and I moved the "system - Profile URL" plugin in first position. When I type some users direct URLs I get to a blank page (error 404 when the system plugin wasn't in first position). Some sample profile URLs not working (all of them aren't):
https://sviluppo.cucina.it/adriano
https://sviluppo.cuc[...]na.it/nonnanora