Logstash Lumberjack Input Stops Processing

I tried to edit /etc/init.d/logstash on line 45, and add -w 12 as follows

 args="agent -f ${LS_CONF_DIR} -w 12 -l ${LS_LOG_FILE} ${LS_OPTS}"

then restarted the service but it doesn't add "-w 12", not sure why!