cannot add trigger for type log

[denso]

I have setup the log function for zabbix on version 1.1.6 and have attempted to write a trigger against this item and get the error:

No such host (Unix_t) or monitored parameter (log[/var/log/messages])

here is the trigger I wish to write:
{Unix_t:log[/var/log/messages].str(error)}&{Unix_t:log[/var/log/messages].str(dev)}&{Unix_t:log[/var/log/messages].str(sector)}=1

here is the simple one i was testing:

{Unix_t:log[/var/log/messages].str(error)}=1

any ideas what I'm doing wrong ??