1. Input error: ensure that the UKey taxpayer identification number entered is correct, and the system cannot identify or verify the wrong identification number.

2. System problem: it is an error prompt caused by system failure or maintenance. In this case, please try again later, or contact the relevant tax authorities or technical support departments for more assistance.

3. Registration problem: If it is a newly registered taxpayer, it will take some time to find the taxpayer identification number in the system. It will take some time for newly registered taxpayers to process and review before they can formally register in the tax system.