That was my thought too, so I had allready checked these. Now that you asked I did the test again. Here it is:
1) Plug the power meter to the wall and have nothing connected to it and see if there is any kind of power consumption?
0 watt
2) Plug on only the power supply cord into the power meter and see if there is any power consumption?
cord unplugged from pc end 0 watt - cord plugged in again 16 watts, 230v, 0.07amp (switch to 'OFF')
3) Have you tried to plug anything else into the power meter?
I use it from time to time and gives reasonable readings, raspberry pi 4watts, hp printer soft off 10 watts, speakers, desk lamps, washing machines etc.
Can you cross check this?
the meter is this: http://www.chacon.be/media/sync/54355/From%20Chacon/54355%20User%20Manual%20EN%20%28old%29.pdf
Thanks for your time.