Safety Minder doesn't allow me to use the Norton account

I have problem set up Safety Minder on my son’s desktop after reinstall. It always saying “This email address is already associated with your Norton Account, an account that was probably created when your registered another Norton product like Norton Antivirus or Norton 360. Please type the password for your Norton Account.” But even if I typed in the correct email and password it still stays on the same page. This email and password was OK to logon my Onlinefamily account. Please help.