1. Restrict transaction types: One of the reasons why GDB card 57 is not allowed to trade may be that this transaction type is restricted by banks, such as high-risk transactions such as buying lottery tickets and gambling.

2. Exceeding the credit limit: If your credit card has reached or exceeded the credit limit, it may also lead to 57 cases where transactions are not allowed.

3. Bank's risk control strategy: the bank will conduct risk assessment according to the customer's credit status and trading behavior. For risky transactions, banks may take restrictive measures, resulting in 57% transactions not allowed.

4. Abnormal credit card status: The credit card status is abnormal, such as loss reporting, freezing and payment stopping. There will also be a prompt that 57 transactions are not allowed.

5. System failure: Sometimes, the failure of the banking system may also lead to 57 transactions that are not allowed.