Usually when you get silence like that, especially from a snmpwalk or snmpget, it means that the device isn't getting your query, isn't using the snmp version you think it is, isn't configured to accept queries from your IP address, or isn't accepting your community.
Confirm that snmp is on, that the version and community is correct, that any query-based restrictions permit queries from your IP address, and that you are querying both the device and the part of the MIB you think you are.
A good basic query for most snmp v1 devices is:
# snmpwalk -v 1 -c public $IP .1
...substitute for "public" and $IP as appropriate.
Although it may not be exactly what you want, this is the snmpd.conf file that I use on Linux nodes that are being queried by cacti:
syslocation System Location
# sec.name source community (password)
com2sec Mybox localhost public
com2sec cacti <you ip> public
com2sec Outside default public
# group.name sec.model sec.name
group RWGroup v2c Mybox
group ROGroup v1 cacti
group ROGroup v2c cacti
group Others v2c Outside
view all included .1 80
view system included system fe
# context sec.model sec.level prefix read write notif
access ROGroup "" any noauth exact all none none
access RWGroup "" v2c noauth exact all all all
access Others "" v2c noauth exact system none all