When you click on a PayPal button and get an error screen that says "unknown" or similar message, this means that PayPal is unable to process your request. This may be due to maintenance to the PayPal system, overloading of the PayPal checkout system, or other PayPal problems.
This is not a DPD error. We can not do anything to fix this error screen- It is a PayPal error.
We apologize in advance if you receive this error, but generally this is a temporary condition and it goes away after a few minutes when PayPal fixes whatever is broken on their end.