SNMP not responding

[Techbart]

I've installed SNMP on a pretty clean copy of Gentoo, with minimal services running alongside, such as apache, samba, teamspeak and a Minecraft server. Otherwise it's as close to core as I can manage, no X11, no SELinux or IPtables. However, after installing SNMP and attempting to use its example conf file, I can't get a response from snmpwalk. I've tried altering the example file, following various versions of an snmpd.conf file from other Gentoo users, even resorting to using just "rwcommunity public" as the only line in a snmpd.conf file. Nothing works.

I've established with netstat -tulpen that snmpd is active and using port 161 UDP. I've tried performing exactly the same steps on another Gentoo machine, and snmpd was able to respond immediately to a snmpwalk query, so I'm only left with the conclusion that something in this system is either misconfigured, or interfering with snmp. Been bashing my head on this for the best part of a day, so any help would be muchly appreciated. Cheers!