Zombie mode dificulty

Ok i saw the profile of myself and i saw hard difficulty but when i m making new room there is not exsist the hard difficulty.Do i need to reinstall my game or that is the main problem of CF.(also just wondering why the easy game is more likely normal mode and normal as hard mode :S)
i just have strange feelings that new mode is messd up because on normal mode i have a hunch like i m playing a hard mode.