1. The courier number queried is incorrect.
2. The logistics company has not uploaded the logistics information to the system.
3. The express delivery number has exceeded the query validity period.
4. The logistics company has not opened such express inquiry service.
5. The used logistics query website is broken.
6. The personnel of the logistics company made a mistake and did not upload the logistics information to the system.
7. Logistics company personnel failed to update logistics information in time.
8. An accident happened in the logistics company, which caused the logistics information update to fail.