It is very common for China Merchants Bank credit card holders to encounter transaction failure when using the bank's credit card, which is generally caused by the following reasons. You can recall whether your credit card situation meets:

First, you just got this CMB credit card, but it has not been activated (opened);

Second, when you use this CMB credit card to operate on the POS machine, the machine breaks down or the credit card line is busy;

Third, the available balance of this China Merchants Bank credit card you used is not enough to support your transaction.

Different scenarios correspond to different solutions, please analyze the specific problems.