I've used CCbill for many internet charges/sites and have had no problems. Just make sure you print or write down the information given if you ever need to cancel a membership.
So why doesn't green dot work? They are just debit cards that you can load with however much cash you want, then it acts like a credit card.. I wonder if you didnt go online and setup your profile, they say if you don't do that then online purchases will fail..