Smart Flex : eligible properties

Hello for everyone. In this moment i have my first property in booking.com. When i tried to configure all my rules, i found the Smart Flex Reservation Programme and it is so interesting for me. But when i tried to active the programme, next to the "Activate now" button there is a massage : "Your property is not eligible for this programme. Learn more". Then i explore the "Learn more" link and i dont find any recommendation related with my property in order to activate the programme. Can anyone help me please?