Trigger system.users.num wan't work

[setevoy]

Hi.

I want to set `ALARM`, if there is more than one user logged to server.

I used trigger with expression:

{venti:system.users.num.last(0)}>0

for test, but - I still haven't any `Event`. Trigger connected to my host, no errors in both Agent or Server logs.

What I'm doing wrong?

Other triggers works good.

Thanks.

P.S. Zabbix 2.4, OS CentOS 6.5