There are several ways of processing CC's. One way is to do it in 2 steps - authorize (check that card is valid and reserve the funds), then capture (take the funds). An authorization reduces the spending limit of your card, but expires after about 30 days if not captured. I have a number of Paypal clients who report that Paypal doesn't work correctly with simple authorizations, in which case your only recourse would be to badger Paypal support until they give your money back, since the merchant (pool in this case) did not actually capture your funds.