How to enable reliable syslog on Version: FortiGate-VM64-AWSONDEMAND v6.0.3,build0200,1810

Hi folks, here is the version of fortigate (aws)

FGTAWS000B061CCC # get system status
Version: FortiGate-VM64-AWSONDEMAND v6.0.3,build0200,181009 (GA)
Virus-DB: 1.00000(2018-04-09 18:07)
Extended DB: 1.00000(2018-04-09 18:07)
Extreme DB: 1.00000(2018-04-09 18:07)
IPS-DB: 6.00741(2015-12-01 02:30)
IPS-ETDB: 0.00000(2001-01-01 00:00)
APP-DB: 6.00741(2015-12-01 02:30)
INDUSTRIAL-DB: 6.00741(2015-12-01 02:30)
Serial-Number: FGTAWS000B061CCC
IPS Malicious URL Database: 2.00183(2019-01-03 09:45)
Botnet DB: 4.00405(2019-02-01 10:00)
VM Resources: 1 CPU, 2006 MB RAM
BIOS version: 04000002
Log hard disk: Available
Hostname: FGTAWS000B061CCC
Operation Mode: NAT
Current virtual domain: root
Max number of virtual domains: 1
Virtual domains status: 1 in NAT mode, 0 in TP mode
Virtual domain configuration: disable
FIPS-CC mode: disable
Current HA mode: standalone
Branch point: 0200

I need to enable reliable syslog, this is how my syslog configuration looks like

FGTAWS000B061CCC (setting) # show
config log syslogd setting
    set status enable
    set server "ServerName"
    set port 7000
end
FGTAWS000B061CCC (setting) #

I tried to provide the command set reliable enable but does not work and get the below error:

FGTAWS000B061CCC # config log syslogd setting

FGTAWS000B061CCC (setting) # set reliable enable

command parse error before 'reliable'
Command fail. Return code -61

FGTAWS000B061CCC (setting) #

I was following this article https://kb.fortinet.com/kb/documentLink.do?externalID=FD32787 but seems like the way to setup the reliable flag is not working.

Thanks in advance.