Why does snmp fail to use its own MIBs?

I've done a fresh install of Ubuntu 12.04LTS, and installed the snmpd and snmp packages.

If I type:

snmpwalk -m ALL -v2c -c public localhost 1.3

I get swathes of errors, of the form:

Cannot adopt OID in SQUID-MIB: cacheClients ::= { cacheProtoAggregateStats 15 }
Cannot adopt OID in NET-SNMP-EXTEND-MIB: nsExtendLineIndex ::= { nsExtendOutput2Entry 1 }
Cannot adopt OID in NET-SNMP-EXTEND-MIB: nsExtendOutLine ::= { nsExtendOutput2Entry 2 }
Cannot adopt OID in UCD-SNMP-MIB: laIndex ::= { laEntry 1 }
Cannot adopt OID in UCD-SNMP-MIB: laNames ::= { laEntry 2 }
Cannot adopt OID in UCD-SNMP-MIB: laLoad ::= { laEntry 3 }
Cannot adopt OID in UCD-SNMP-MIB: laConfig ::= { laEntry 4 }
Cannot adopt OID in UCD-SNMP-MIB: laLoadInt ::= { laEntry 5 }
Cannot adopt OID in UCD-SNMP-MIB: laLoadFloat ::= { laEntry 6 }
Cannot adopt OID in UCD-SNMP-MIB: laErrorFlag ::= { laEntry 100 }
Cannot adopt OID in UCD-SNMP-MIB: laErrMessage ::= { laEntry 101 }
Cannot adopt OID in NET-SNMP-AGENT-MIB: nsNotifyRestart ::= { netSnmpNotifications 3 }
Cannot adopt OID in NET-SNMP-AGENT-MIB: nsNotifyShutdown ::= { netSnmpNotifications 2 }
Cannot adopt OID in NET-SNMP-AGENT-MIB: nsNotifyStart ::= { netSnmpNotifications 1 }

There a literally hundreds of these.

If snmp doesn't even like the distro-included MIBs, what chance to I have of getting my own used? (I get the same form of error with my own MIB, on a different machine, which is why I set up a clean install to test the distro's sanity.)

Do other distros have this issue? Is there something obvious that I am overlooking here?

apt-get install snmp-mibs-downloader

The above command downloads various non-free MIBs which the free MIBs (included with distro) require to work.

There are still a handful of errors, after installing this non-free package, but the snmpwalk now works.

It seems you do not have snmp installed. Just do

sudo apt-get install snmp