"OID not changing" error in SNMP discovery rule

[Rémy]

I create this Discovery Rule :

SNMP OID : discovery[{#VALUE},UPS-MIB::upsInputVoltage]

I've got this error : "OID not changing"
When I check the source code (checks_snmp.c), it seems that the OID doesn't change.

When I run this command, everything is OK :

snmpwalk -v 2c -c public x.x.x.x UPS-MIB::upsInputVoltage
UPS-MIB::upsInputVoltage.1 = INTEGER: 237
UPS-MIB::upsInputVoltage.2 = INTEGER: 237
UPS-MIB::upsInputVoltage.3 = INTEGER: 234

I don't know how to resolv this issue.

Zabbix 3.2.1

Thanks

Rémy