Problem with Alarm of VEO 180NX

I have a problem with my VEO 180nx, my alarm is off and is impossoble to change to on.
Whith the veo is not possible change to on because it don´t have the option.
Whith the Oceanlog the option don´t run good and don´t save this setting (Alarm on) in VEO
Now I am diving with Nitrox and this alarm is very important for me
I think that when I changed the units to metric the alarm changed to off forever.
Thanks

Unfortunately, I think you've got to get it back to us for service. There is no set option - either on the unit or via OceanLog, so I suspect there is something physically wrong with the alarm.

Thanks for answer me.

Is not a physically problem because the alarm is working correcly, when I turn on the VEO 180 the alarm past the test and I can hear it and at same time I can see the Led Working.
In my family have three VEO, two VEO 180Nx whith the same problem, and the third I never connect to the Oceanlog and no problem at the moment.
Two months ago after a long time whith the battery out, the veo return to factory settings, and the alarm work correctly but when I change the imperials units to metric units, the alarm and led of the VEO 180 don´t work any more.
Is possible for me return to factory setting? Whith this I Was a happy men.