Error when creating a child account

I can get all the way through the directions for creating a child account (Settings, family, etc.), but when I put in my verification code from Paypal I get the error: "An unknown error has occured." Credit card(s) has same error. Already restarted the phone. Also tried turning wifi off and just using my mobile data. Have also tried on different days. I get the same error each time. Any ideas?