I am getting a null pointer exception in statement :

  SnmpVar var = result.getVariable(oid);

 

for snmp v3 that is

pdu.setCommand(SnmpAPI.GETNEXT_REQ_MSG);

 

while with 
 pdu.setCommand(SnmpAPI.GET_REQ_MSG);

 i can get values .

 

Does anybody have a idea what could be the problem.....