Condor uses Share*It for payment processing and electronic delivery.
Share*It's payment processing servers are actually in Germany since
this is a German based company and they seem to have problems at times
with their system rejecting international transactions even when your
bank says that they didn't block anything or never even received a
transaction request.

I didn't have any problems purchasing Condor but when I got a new
license key for SeeYou (Naviter uses Share*It as well) I had all kinds
of problems with my (US) credit card being denied even after I called
my bank to make sure that they didn't block the transaction for
whatever security reason. I eventually managed to get the payment
through using a different (US) card from a different bank.

Try a different card and have a word with your bank to make sure that
they didn't block it because of a German IP address requesting the
transaction. It can get pretty frustrating if you are trying to do a
simple and fully legitimate $50 transaction and end up fighting global
fraud protection routines on several levels...

Markus