How do i use my MasterCard debit card to purchase Fishin’ 2 go full on Motorola Droid Android Market?

I have no idea how to get it to work….
it seems to me that you are only able to use a credit card for it… why is that?
i will try to just enter my debit card info to see if its accepted as credit… idk…

Should be same as using a credit card–only you have to use your pin number.