Snmpset not working for shell script

I made the following shell script to perform a simple operation.

#name file: /etc/snmp/
id = $1
ping id


chmod a+wx

I also config setting the in "/etc/confing/snmp"

config extend
        option name 'testset'
        option prog '/bin/sh'
        option args '/etc/snmp/'
        option group 'private'
        option secname 'rw'
        option community 'private'

now, i want to input it with this command

snmpset -v2c -Ir -c private NET-SNMP-EXTEND-MIB::nsExtendInput."testset" s ""

but i get error

NET-SNMP-EXTEND-MIB::nsExtendInput.testset: Unknown Object Identifier (Index out of range: testset (nsExtendToken))