even 3 security questions answered I cannot buy apps nor redeem vouchers

Dear community,

I am running iTunes 11.0.2 on a Windows Vista Ultimate computer. I have recieved a voucher for an App and I would like to redeem it. I am redirected via the voucher link from my email inbox to the iTunes Store, then the voucher code is inserted automatically into the mask of iTunes. The mask with the voucher code is then surrounded by a red rectangle and a text apperars that I have to choose 3 security questions first and store my answers to them. Searching for a while I found appleid.apple.com, where I proceeded as requested. I selected 3 questions, after each answer I stored the answer.

Going back to to redeem the voucher the same process happens again and again, also after days. I tried the same process on Mac 10.8 system without success however, no difference in the behaviour.

If I try to buy another App in the iTunes store the same question to answer 3 security questions appears.

If seems, like appleid.apple.com and my iTunes account are not connected and not synchronized. It is also confusing that my short nickname which I choose to write this question in this discussion board does not appear in my iTunes account, even I use the identical username / password combination for the iTunes account as well for the discussion board here.

I would appreciate any help of you to overcome this dead end road.

Cheers, Nui