/ZWaveAPI/Run/devices[2].instances[0].commandClasses[0x20].Set(255)
Answer :
Error 500: Internal Server Error
Uncaught TypeError: Cannot call method 'Set' of undefined
In fact, it seems the same problem as here : http://en.z-wave.me/content/documentation-wrong
But his solution doesn't work for me.
While checking and preparing my post here, I found my solution by myself.
By checking my console, It's 0x25 commandClasses which is used !
see below :

xx/ZWaveAPI/Run/devices[5].instances[0].commandClasses[0x25].Set(255)
Indeed, this url works...
Switch: Everspring AN157
Can somebody explain why ?
I also still have my problem with my everspring st814, which failed to complete interview...
Thank you...