fwpolicy-implicit-log activation in FortiOS through Fortimanager

[atefeh]

Dear,

I would like to activate following log options in one of the FortiGate (fortiOS 5.6.5) vdom through running the scripts in Fortimanager.

config log setting 

set fwpolicy-implicit-log enable  et fwpolicy6-implicit-log enable  end 

The scripts run correctly and all other configurations are installed in FortiGate, except these two parameters.

These parameters are relevant to the "implicit policy" which is by default is there.

Could you PLZ advice me what could be the issue?

Many thanks