The working principle of Niu Card is this: bind your email address for receiving credit card bills, it will automatically search for credit card billing information from all your emails, automatically process the data, and display the results in Niu Card. on the card interface. If it cannot be synchronized, it depends on the situation. First check whether your credit card is set up to receive bills by email. If it is confirmed that there is an email to receive the bill, check which email it is and whether it is the email you bound. If not, you can Bind your credit card bill receipt email address. Just synchronize again.