1. The available quota is insufficient. Credit cards have an available limit, and once it is exceeded, you cannot make purchases with the card.

2. Online payment limit. Each credit card has a limit for online payment. Once reached, this credit card can no longer be used for payment. Based on the above situation, you can log in to the official website of Ping An Credit Card and click Ping An One-Connect Online Banking to check the available limit and whether there is a limit setting for the online payment limit.

3. POS machine merchants and line problems. It may be that the merchant's POS machine does not support Ping An Bank credit cards, or it may be a line problem with the POS machine.

4. Credit card magnetic stripe problem. If the credit card does not have magnets, it will not be possible to swipe the card. In this case, you need to replenish the magnets or replace the card.

5. The credit card has expired. Credit cards also have an expiration date. After the expiration date, the credit card cannot be swiped.