Problem with registration page

The problem was the mod_rewrite of Apache. I went in /etc/apache2/sites-available/000-default and I changed

Options Indexes FollowSymLinks MultiViews
AllowOverride None
Order allow,deny
allow from all

to

Options Indexes FollowSymLinks MultiViews
AllowOverride all
Order allow,deny
allow from all

the I restarted the apache server and all gone fine.