Zabbix 2: Trigger expressions not working 100%?

[mgibson]

I've got the following Trigger expression:

{EXCHSVR:eventlog[Application,,"Warning|Error",,,,].logeventid(1173)}=0 &
{EXCHSVR:eventlog[Application,,"Warning|Error",,,,].logsource("BlackBerry Messaging Agent EXCHSVR Agent 1")}=0 &
{EXCHSVR:eventlog[Application,,"Warning|Error",,,,].logsource("SQLWRITER")}=0 &
{EXCHSVR:eventlog[Application,,"Warning|Error",,,,].logsource("BlackBerry Router")}=0

but it doesn't seem to be working as expected. My expectation is that the trigger should only fire if the Event ID isn't 1173, AND the Source isn't "BlackBerry Messaging Agent EXCHSVR Agent 1" AND the Source isn't "SQLWRITER" AND the Source isn't "BlackBerry Router".

I'm still getting alerts for events coming from the "SQLWRITER" source, and I'm not sure if I'm doing something incorrect, or I've encountered a bug.

Also, can you use brackets inside these expressions? I'd like to be able to do X AND (Z OR Y), but I'm not 100% sure how you would accomplish that.

Thanks!