The card can't be used for the following reasons \x0d\ First, the card status is abnormal, such as degaussing the card and chip damage \x0d\ Second, the card doesn't support transactions, such as the card with VISA single logo /JCB single logo, and it doesn't support UnionPay transactions or some online transactions \x0d\ Third, there is nothing wrong with the card, and the POS machine signal is not good, so the off-line transactions will also fail. \x0d\ IV. IC chip credit cards. Since UnionPay has turned off the downgrade transaction function, if the cashier still swipes the card instead of inserting it, it will also lead to the inability to use \x0d\ V. Some overseas websites do not support credit cards issued in China or credit cards issued by CCB \x0d\ VI. The credit card limit is insufficient.