SNMP FREENAS-MIB not working

I can not monitor ZFS through SNMP.

When I run the following, I have no problems.

[root@zabbix ~]# snmpwalk -v 2c -c public 192.168.40.40 IF-MIB::ifDescr
IF-MIB::ifDescr.1 = STRING: ix0
IF-MIB::ifDescr.2 = STRING: ix1
IF-MIB::ifDescr.3 = STRING: bge0
IF-MIB::ifDescr.4 = STRING: bge1
IF-MIB::ifDescr.5 = STRING: lo0
IF-MIB::ifDescr.6 = STRING: pflog0
IF-MIB::ifDescr.7 = STRING: lagg0
IF-MIB::ifDescr.8 = STRING: vlan10
IF-MIB::ifDescr.9 = STRING: vlan40
IF-MIB::ifDescr.10 = STRING: vlan60
IF-MIB::ifDescr.11 = STRING: vlan110
IF-MIB::ifDescr.12 = STRING: vlan120
IF-MIB::ifDescr.13 = STRING: ue0

Anything that has to do with FREENAS-MIB does not work.

[root@zabbix mibs]# snmpwalk -v 2c -c public 192.168.40.40 FREENAS-MIB DEFINITIONS::zfsArcSize
FREENAS-MIB: Unknown Object Identifier (Sub-id not found: (top) -> FREENAS-MIB)
[root@zabbix mibs]# snmpwalk -v 2c -c public 192.168.40.40 FREENAS-MIB::zfsArcSize
FREENAS-MIB::zfsArcSize = No Such Object available on this agent at this OID
[root@zabbix mibs]# snmpwalk -v 2c -c public 192.168.40.40 FREENAS-MIB::zfsArcSize
FREENAS-MIB::zfsArcSize = No Such Object available on this agent at this OID
[root@zabbix mibs]# snmpwalk -v 2c -c public 192.168.40.40 FREENAS-MIB::zfsArcSize
FREENAS-MIB::zfsArcSize = No Such Object available on this agent at this OID
[root@zabbix mibs]# snmpwalk -v 2c -c public 192.168.40.40 FREENAS-MIB::zpoolReadBytes
FREENAS-MIB::zpoolReadBytes = No Such Object available on this agent at this OID
[root@zabbix mibs]# snmpwalk -v 2c -c public 192.168.40.40 FREENAS-MIB::zpoolWriteOps1sec
FREENAS-MIB::zpoolWriteOps1sec = No Such Object available on this agent at this OID

I think something is broken.