MacMini won't go to deepsleep mode

I have a MacMini Late 2012 with 16 GB RAM. I changed the hibernatemode to 3 (sleep and hibernate) using:

pmset -a hibernatemode 3

then verified the change was actually made using:

pmset -g | grep hibernatemode

Then downloaded the DeepSleep widget and activated it. It said "going to sleep", the monitor went off and that was all. I then powered off the mac and then powered on again, but the mac just booted up from scratch instead of return from hibernation.

Did I miss something here?

Victor