Wehn Stubhub upgraded their website some of the default information was lost. Make sure there is a default payment account chosen for your account even if you only have one account listed. I have heard that this tends to fix the problem.
We are changing the way you register and sign-in to the StubHub Community. After the switch, you will enter the email address you use to access the community in order to reset your password. You will enter your community username and new password and done!