1. system maintenance of the payment company: sometimes the payment company will upgrade or repair the system, resulting in the failure to connect the server and upload or download the data, which leads to the failure of the credit card to display the transaction on the pos machine. Confirm the system maintenance time of the payment company and wait for a while before trying to swipe the card.

2. transaction amount limit: some banks have restrictions on the amount of a single transaction, such as the minimum and maximum amount of a single transaction. If the transaction amount of a credit card swiping pos machine exceeds or falls below these restrictions, the transaction fails. Check your own transaction limit to ensure that the transaction amount is within the range specified by the bank.