I have configured this trigger :

{MySnmpHost:cpu.idle.percent.nodata(900)}=1

My cpu.idle.percent item is a SNMPv3 authPriv one (polling : 300 seconds).
I fill authPriv parameters with bad credentials (Security name, Authentication passphrase and Privacy passphrase).

I expect that my trigger change to PROBLEM state (because there is no data) but it never happens.