Currently Being ModeratedMay 1, 2013 5:03 PM (in response to Robert RTP)
In-App purchase needs a valid credit card link to your Apple ID.
If you have the above:
Check your iPad's Settings > General > Restrictions: shoud be off > In-App Purchases: should be on.
Currently Being ModeratedMay 3, 2013 3:38 AM (in response to Robert RTP)
These are effectively user-to-user forums, with only limited posts from Apple.
You can contact iTunes support via this page and ask them why the message is appearing (we won't know why) : http://www.apple.com/support/itunes/contact/ - click on Contact iTunes Store Support on the right-hand side of the page, then try selecting Purchases, Billing & Redemption