1. The barcode is not scanned correctly: Please make sure that your mobile phone or scanner scans the barcode correctly and the barcode is clearly visible.
2. Bar code damage: If the bar code is damaged or blurred, it may lead to incorrect scanning. Please try using a different barcode or contact the relevant department for help.
3. System failure: If the system fails, the barcode may not be displayed correctly. Please contact the relevant departments for help.
4. Database problem: If there is a problem with the database, the barcode may not be recognized correctly. Please contact the relevant departments for help.
If the above methods can't solve the problem, I suggest you contact the local vaccination agency or relevant departments for help and solutions.