pb with return code ssh custom script

Hi, if the error code is greater than 1 (warning level), i got error.

The SSH script's "returncode" has to be one of the following values: Value Description

0 OK

1 WARNING

2 System Error (e.g. a network/socket error)

3 Protocol Error (e.g. web server returns a 404)

4 Content Error (e.g. a web page does not contain a required word)

This is my script on AIX6.1 :

FS=$1

USEFS=`df -g  | awk '{print$7,$4}' |grep -v grep | grep $1 |awk '{print $2}'|awk -F'%' '{print $1}'`

if [ ${USEFS} -gt 50 ]

then 

echo "4:${USEFS}:KO"

else

        echo "0:${USEFS}:OK"

fi

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i have the fault code : (code: PE024)

custom script ssh