We are aware that many of you have run into the issue of getting an "Invalid Credit Card" message when trying to register.  We apologize for this erroneous message and inconvenience.  While we work toward a solution, we do have a workaround that you may use.  Here are the steps:

  1. Go to https://account.microsoft.com/PaymentHub/
  2. Sign in with your Windows Live ID (the one used to register with App Hub)
  3. In the upper-right hand corner, make sure your "Personal Account" is selected (NOT the "Business Account").
  4. Go to Payment Options, where you will see "add payment option" near the bottom of the screen on the left side.
  5. Add your credit card.
  6. Return to App Hub and continue your registration.  If you are already logged into your App Hub account, click your name in the upper-right corner to walk through the registration steps to complete the process.

Also please be mindful that your country information must be aligned between your Windows Live ID (including any other services, such as XBox, associated to it), the information entered into App Hub and the Credit Card.  Any inconsistencies may cause an issue with the process.

Read the full post here.