What can I do if my printer is not recognizing the new drum unit?

1. Check the connections between the drum unit and the printer.
2. Ensure the drum unit is firmly locked into place in the printer.
3. If using a third-party drum unit, ensure it is compatible with the printer.
4. Restart the printer.
5. Reinstall the drum unit in the printer.
6. Check for a new or updated printer driver.