Since the DIY forum in area 51 is in the private beta stage, i think this is the site to ask this question, a very easy one.
I've this adapter
And let's just say that I can't screw the outlet screw through the adapter metal ground hole.
What I did was connect cable to the adapter metal ground hole and connected the other end of the cable to a metal plate that is screwed to a concrete wall.
Is that ok? i don't get any shock or wiring warnings that i did get before without the ground cable.