The reasons include: exceeding the repayment limit and bank card problems.

1. Exceeding the repayment limit: WeChat Wallet has certain restrictions on credit card repayment. If the credit card repayment limit of WeChat Wallet is exceeded, repayment cannot be made.

2. Bank card problems: If there is a problem with the bound bank card, such as insufficient balance, frozen card, etc., it will also result in the inability to repay.