Thanks Rob for quick reply.
I download MIB’s from vendor’s website. The switch I’m trying to work is CISCO SG300-28MP 28-Port Gigabit PoE Managed Switch and here the link for MIB http://software.cisco.com/download/release.html?mdfid=283019666&softwareid=283415684&release=1.3.0&relind=AVAILABLE&rellifecycle=&reltype=latest
There are so many files and I confused which one should I import first for that switch. The error message I received while I was trying to import CISCOSB-mib.
Thanks for your help ROB.