snmpd -verify if the mibs are loaded.
If you are setting up the snmpd server and have added your own mibs and do not really know if the mibs are loaded or not then simply go to the directory:
/var/lib/net-snmp/mib-indexes
This can save you a lot of time, if you are not getting results with snmpwalk. You can even use snmpwalk as :
snmpwalk -v -c
Well, these little things can save you a lot of time 🙂