E1525 IKEA TRADFRI motion sensor (occupancy)

Hi, this is my first post so I apologize if…

I read about a special attribute on the Tradfri Motion device but I wonder id this is really available since from my mosquitto publish this informations seems not to be present
This attribute is a boolean value exposing a dark status

How to make this available?
Donìt know if this is model dependent since there two motion sensor models