Trigger for windows event logging gives error in server log.

[stefaan.plets]

I'm new to Zabbix, and have spent quite some time trying to make Windows event logging work.

On Zabbix 1.4.4, I created this trigger in my Template_Windows:

({Template_Windows:eventlog[System].logseverity(4)}>1) & ({Template_Windows:eventlog[System].nodata(30)}#1)

This trigger seems to work; the trigger changes its value from time to time;

But when I watch the Zabbix server log; I get these warnings:

Expression [({20597}>1) & ({20596}#1)] cannot be evaluated [Unable to get value for functionid [20597]]

Evaluation of expression [({20597}>1)&({20596}#1)] failed [Unable to get value for functionid [20597]]

Unable to get value for functionid [20597]

Am I doing something wrong here?