Folks get their terms mixed up. Are you referring to a prepaid card or a real debit card associated with a bank account. Prepaid cards, gift cards and one-time-use cards always cause issues. If your account is properly setup and verified, meaning you have a bank account and credit card linked, there's usually no issues. When it comes to making a purchase, PayPal will first try to withdraw funds from your PayPal Account balance, if there are insufficient funds, PayPal will then withdraw funds from your bank account. The reason you have a credit card linked for additional personal security and you can then use that card as an option for payment during the check out process. Any other type of card linked to your account usually cause some kind of issue similar to what you are experiencing. The exception is PayPal products or Green Dot Money Cards. Sorry, can't explain PayPal's logic or their security model here but, if the account is setup as mentioned above (bank account and credit card), everything works much better.
