The value Error, on a supply indicates that a value is not available.
- Device not able to communicate specific supply level over SNMP protocol
- Device is in low power mode and does not send complete information for supplies
- Supply smart chip may have bad connection, re-insert the consumable 
- Supply has an error and can be resolved after replacing
- Printer firmware version does not support level reading in the supply (possibly out-dated)

Ensuring the printer firmware is up-to-date can be very helpful when the printer is accessed and information is gathered to present accurately on your account(s).