XPS 13 7390 shourcut key Fn+h not work

Hello to everybody,

i have buy two day ago this notebook. I have read the manual and sinilarly to my old inspiron 7373 there is the possibility to switch from HD activity using the key combination FN+H, but this not work for me (remain in the charge battery activity and not swith). I remember that this function work well in my inspiron.

There is some trik for solve this issue? There is some software to install for fix this situation ?