[Does counting cards still work?!]

yesterday, i tried to count cards with myself as the dealer and player i played with one deck, and of course with the counting rules (1-6 : +1; 7-9 : 0; 10 - ace/king/queen: -1). I wanted to test the strategy first, before playing for real. 

 

I started dealing the cards... 

short story is that house won 8 times and i only won 2 times, although i did count each and every card correctly! 

 

So my question is wether counting cards actually works?