I am having problems with paying since I live in germany and am paying with us credit card. wont' take it. tried the fix, now it gives error message that zip code is ?

We accept credit, debit, and pre-paid cards with a Visa, MasterCard, American Express, or Discover logo. Like many other U.S. online merchants, we can only process cards with a U.S. billing address. 

If you do not have a US billing address, perhaps you have a friend or relative in the US that could assist you. 

I am using a relatives credit card and it still wont accept my payment.

Just for purposes of getting this payment through, change your personal mailing address (Mailing address interview in Personal Info tab) to the US mailing address and zip code you are using for the credit card.

After completing the payment, but before filing, change your personal mailing address back to your actual foreign mailing address.