Is the Mastercard attached to your Paypal account? There is no reason to give the card number to Paypal once it is registered. It will be used automatically.
Or are you trying to use MC directly to pay your seller. Most eBay sellers don't have merchant accounts, unless they also have a B&M business. We use PP to process credit cards for us.
Use Contact Seller to explain the delay and make sure your cc is attached to PP. This can take a couple of days. They prove identity by depositing a tiny amount to your card and once you verify the amount, they take it back.
Or is the seller the problem? Is he Not A Registered Seller? If so, thank your lucky stars that PP and eBay protected you from what was probably going to be a Bad Deal.
