Customized-script for nagios problem

[criver]

check-errors OK 07-21-2009 10:32:39 0d 2h 1m 45s 1/4 (null)

why the Status Information is null????

here is my script: /usr/local/nagios/libexec/check_errors

#!/bin/bash

FILE="/usr/local/nagios/libexec/err_counts.txt"

if [ $# -lt 2 ]
then
echo "Usage:$0 -w num1 -c num2"
exit 777
fi

OK=0
WARNING=1
CRITICAL=2

ERROR1=`cat err_counts.txt`


ERROR2=`grep -i error /var/log/messages -c`


ERROR3=`echo $[$ERROR2-$ERROR1]`


`grep -i error /var/log/messages -c > $FILE`

if [ $ERROR3 -lt $1 ]
then
echo "OK error counts $ERROR3"
exit $OK
fi

if [ $ERROR3 -gt $1 -a $ERROR3 -lt $2 ]
then
echo "Warning error counts is $ERROR3"
exit $WARNING
fi


if [ $ERROR3 -gt $2 ]
then
echo "Critical error counts is $ERROR3"
exit $CRITICAL
fi