Net-snmp with node js

Hello I want to test my bandwith using ifHCInOctets and ifHCOutOctets'OID. But the problem is the value is not recognized. For information I created my session with this code:

var snmp=require("net-snmp");

var options = {

port: 161,
retries: 1,
timeout: 5000,
transport: "udp4",
trapPort: 162,
version: snmp.Version2c

};

var session = snmp.createSession ("127.0.0.1", "public",options);

via Ariscreamo