Just to notice that the instuctions in my case where not clear. In Fibaro documentation, it’s written to click Button B, in fact, after 2 hours trying to pair and nothing happends, I look in other domotic forum, and you have to click quickly 3 times Button B in order to pair your device, thanks Fibaro for the good quality of their devices ;), but what a poor documentation >:(
You might have misunderstood it but to add the device you have to press 3 times the switch button or… one time the little B button. 
@Throttleman
No, it never work pushing 1 time little button B with my Fibaro. And I’ve seen this in different forum, I can send you the link if you want. Maybe only a serie of Fibaro that was wrong?