Thanks for the quick response!

It's the credit card payment option that's giving me fits.
My credit card works great on other sites, Amazon, iTunes, etc., but for some reason, I can't make a purchase for the DLC '39 Campaign.

Hate to hijack this thread . . . But I'm trying to purchase Panzer Corps DLC '39 Campaign and for some reason I can't purchase it. I recheck the fields, make sure everything is correct, hit the 'checkout' button--nothing--just an error message "GC 430409"