I get a lot emails lately that someone tried to pay inside my application with in-app billing and they get a “card not supported” kind of error on the Android in-app billing window. These same people report that they are able to buy other apps directly on Android Market, and with the same card they can’t pay in-app.
I tried to contact Google but no response yet (I will post an update if I get an answer).
Have you experienced something similar? And then some people run into the in-app billing bug, where your order is “pending” and you can’t do anything. I get negative feedback and this is outside my responsibility.
I think I found a solution for my problem. It was most probably caused after we asked Google to transfer the whole Android account to a new gmail address. I have checked the in-app products in the Android Market console and the the price field was empty on the new account! Only the country specific prices were set. I am pretty sure that the price was set before the account was changed. So I edited the product and entered a price and I asked a customer who previously couldn’t pay to try it again. It worked!
So be sure to check if your in-app products have the price set (and not only the country specific price values).
BTW. Google also changed our public key while switching the accounts. People were complaining the whole day that they paid and didn’t receive the item. Well Google took the money but the information was delivered signed with a new public key and was not recognized on the devices.