Thermostat fan_timer_duration error



I am working in a nest http client for thermostats and everything seems to be working as expected but I cannot make the fan_timer_duration to work.

I had tried different combinations between fan_timer_duration and fan_timer_active and the call always returns “No write permission(s) for field(s): fan_timer_duration”. If I send only fan_timer_active=true then the fans turns on correctly.

Any ideas??