Are you absolutely sure that your OID is correct ?
Have you tested to read it with a simple command like snmpget to check if the returned value is correct?
Try what number returns oid(“1.3.6.1.2.1.43.11.1.1.9.1.1”) itself.
As I know if it returns negative number (-2 or -3), that means you are using not original toner (refurbished, refiled etc.) and thus you can’t see the actual toner level.
For my printers I use following function (called “toner_percent”):
OID 1.3.6.1.2.1.43.11.1.1.9.1.1 is remaining toner capacity (usually in pages) and OID 1.3.6.1.2.1.43.11.1.1.8.1.1 is maximum toner capacity of the cartridge.
OID 1.3.6.1.2.1.43.10.2.1.4.1.1 is the total number of pages ever printed.