SNMP return 'error

Hi
I'm quite new to this ICINGA and have run into a bit of a problem.

I have written a service:

apply Service "mem-check" {
import "generic-service"

check_command = "snmp"
vars.snmp_oid = ".1.3.6.1.4.1.674.10892.5.4.200.10.1.27.1"
vars.snmp_community = "public"
vars.snmp_version = "2c"
vars.snmp_address = host.vars.ipmi_ip
vars.snmp_miblist = "/usr/share/snmp/mibs/IDRAC-MIB.mib"
vars.snmp_crit = 5
vars.snmp_warn = 4

assign where host.name == "hest"
}

the result is:
services.d # snmpget -v2c -c public hest .1.3.6.1.4.1.674.10892.5.4.200.10.1.27.1
iso.3.6.1.4.1.674.10892.5.4.200.10.1.27.1 = INTEGER: 4

In short: I have a defective memory module.
mib states that INTEFER:3 is OK and INTEGER: 4 is noncrit.

In the dashboard my service returns:
Plugin Output


SNMP OK - 4
and green light.

If I change vars.snmp_warn = "3" I get a yellow light ( which I want )

So my question is:
why does the monitoring tool not report the warning as set in vars.snmp_warn.

Thanx in advance