Omni 2E doesn't recognise power supply

Hi, my omni 2e (4.0B) doesn't recognise if the power supply fails...
 
If I shut down the main supply (230V) the central remains online with the battery but doesn't notify the problem.
In the automation code I inserted the command to send me a mail if the power goes down and comes back... But It doesn't works.
(the modem and the switch are under ups but not the omni2E)
 
Can I solve this?
 
Thanks