So I'm following the instructions in Family Sharing to add a child account who is under 13 years old. After I enter the birthdate, and agree to the Parental Disclosure agreement, it takes me to the credit card screen and says I need to go back into iTunes and add a valid credit card...well, I have a valid credit card. It's the same one I've used for a very long time. I've reentered it literally 25+ times, I've rebooted, I've tried everything I can think of and nothing works. I simply get stuck at the attached screen. Anyone else been able to get past this?