check_win_eventlog help

I'm using the Windows Eventlog Addon for Nagios (http://sourceforge.net/projects/naplax/, version 0.1.0), with the following command definition:

define command{
        command_name    check_win_applicationlog
        command_line    $USER1$/check_win_eventlog -H $HOSTADDRESS$ -s A -l Application -m $USER6$ -t $USER7$ -q $USER8$
}

Where the user macros are defined in resources.cfg as:

$USER6$="+"
$USER7$="+"
$USER8$="+"

This will retrieve all the entries in the application log, which it does just great. My question is how can I filter out entries I don't want to see? I saw the examples where you can ignore everything but xy, but I want to receive all but xy. Anyone know how I can do that? I tried changing the $USER6$ macro to:

$USER6$="+:Error String"

Which, in theory, would get everything except those events that have "Error String" in them, but it's not working that way. Can anyone help me out with this? Thanks a bunch.

Darrell Mozingo