● mango.service - LSB: Start or stop the Mango Automation
Loaded: loaded (/etc/init.d/mango; generated)
Active: failed (Result: exit-code) since Mon 2019-08-05 21:50:50 AEST; 6min ago
Docs: man:systemd-sysv-generator(8)
Process: 764 ExecStart=/etc/init.d/mango start (code=exited, status=127)

Aug 05 21:50:50 debian-mango systemd[1]: Starting LSB: Start or stop the Mango Automation...
Aug 05 21:50:50 debian-mango systemd[1]: mango.service: Control process exited, code=exited, status=127/n/a
Aug 05 21:50:50 debian-mango systemd[1]: mango.service: Failed with result 'exit-code'.
Aug 05 21:50:50 debian-mango systemd[1]: Failed to start LSB: Start or stop the Mango Automation.
screenshot:

below is my mango service file content:
(i played with the path for the commands but ended up with the same message)

*#!/bin/sh
# chkconfig: 235 99 10
# description: Start or stop the Mango Automation
#
### BEGIN INIT INFO
# Provides: mango
# Required-Start: $network $syslog
# Required-Stop: $network
# Default-Start: 2 3 5
# Default-Stop: 0 1 6
# Description: Start or stop the Mango Automation
### END INIT INFO
start="/vwang/mango/bin/ma.sh start"
stop="/vwang/mango/bin/ma.sh stop"
lockfile=/var/lock/subsys/mango
name='Mango'
case "$1" in
'start')
$start>/dev/null 2>&1 </dev/null
RETVAL=$?
if [ "$RETVAL" = "0" ]; then
touch $lockfile>/dev/null 2>&1
fi
;;
'stop')
$stop
RETVAL=$?
if [ "$RETVAL" = "0" ]; then
rm -f $lockfile
fi
;;
'status')
status Mango
;;
'restart'|'reload'|'condrestart')
$stop ; $start
RETVAL=$?
;;
*)
echo "Usage: sudo service{ start | stop | restart | reload | condrestart}"
RETVAL=1
;;
esac
exit $RETVAL*

Please let me know if the service message is correct. If it is not, what do I need to change to make it work.

Thanks in advance.