SNMP NoSuchInstance Exception

Question

I'm using python and pysnmp library. I'm trying to get parameters of service profile from mib browser. i defined SNMP OID groupings in a class.

oidGroups = {
   'serv_profiles': [
       ('xdslRARatioDownstream', 'line.interval', 'ra-mode-down'),
       ('xdslRARatioUpstream', 'line.interval', 'ra-mode-up'),
       ('xdslMinBitrateDownstream', 'line.interval', 'min-bitrate-down'),
       ('xdslMinBitrateUpstream', 'line.interval', 'min-bitrate-up'),
       ('xdslPlannedBitrateDownstream', 'line.interval', 'plan-bitrate-down'),
       ('xdslPlannedBitrateUpstream', 'line.interval', 'plan--bitrate-up'),
       ('xdslMaxBitrateDownstream', 'line.interval', 'max-bitrate-down'),
       ('xdslMaxBitrateUpstream', 'line.interval', 'max-bitrate-up'),
       ('xdslMaxInterleavingDelayDownstream', 'line.interval', 'max-delay-down'),
       ('xdslMaxInterleavingDelayUpstream', 'line.interval', 'max-delay-up'),
       ('xdslMinImpNoiseProtDownstream', 'line.interval', 'imp-noise-prot-dn'),
       ('xdslMinImpNoiseProtUpstream', 'line.interval', 'imp-noise-prot-up'),
       ('xdslErasureDetectionDownstream', 'line.interval', 'inp-wo-erasure-dn'),
       ('xdslErasureDetectionUpstream', 'line.interval', 'inp-wo-erasure-up'),
       ('xdslL2LowPowerBitrateDownstream', 'line.interval', 'min-l2-br-down')
    ]}

    showCommandsSnmp = {
     'service profile': (oidGroups['serv_profiles'], {}, '')
    }

i have method that is getting parameters of profiles(service profile,spectrum profile..) according to given command.(this method is getData() method.)

   rackSnmp = RackoSnmp(resource='212.156.115.8:161')
   res = rackSnmp.getData('service profile', {'interval' : '1'})
   print res.values()[0]

output :

OrderedDict([('ra-mode-down', NoSuchInstance('')), ('ra-mode-up', NoSuchInstance('')), ('min-bitrate-down', NoSuchInstance('')), ('min-bitrate-up', NoSuchInstance('')), ('plan-bitrate-down', NoSuchInstance('')), ('plan--bitrate-up', NoSuchInstance('')), ('max-bitrate-down', NoSuchInstance('')), ('max-bitrate-up', NoSuchInstance('')), ('max-delay-down', NoSuchInstance('')), ('max-delay-up', NoSuchInstance('')), ('imp-noise-prot-dn', NoSuchInstance('')), ('imp-noise-prot-up', NoSuchInstance('')), ('inp-wo-erasure-dn', NoSuchInstance('')), ('inp-wo-erasure-up', NoSuchInstance('')), ('min-l2-br-down', NoSuchInstance(''))])

Values corresponding to keys are not coming. I used same method for 'oparational summary'. It worked. Do you have any idea?

I hope I've explained.