Warning received "It was not possible to finish your purchase"!...

"I re-installed my Angry Birds Apps on my new iPad 3 (IOS 7) (Gratuit downloads) with my Apple ID and password but when I tried to buy additional items (e.g. Tournament Pack for angry Birds Friends) I received the warning that "It was not possible to finish your purchase. For help, please contact iTunes support".
However, I checked my Apple/iTunes Account details and they are all in order, including my credit card details and phisical address.
Can someone please assist?
Thank you.