it will only work on steam/retail v1.70 .. remember to set block type to automatic in game options.
3 reasons it will not work , wrong version of the game , 2 service packs ( they can have memory guards which stop writeprocess memory which will end your hacking career.. the only way to cure memory guarding is to reinstall your os and dont update the service pack ) , and finally your antivirus is rubbish get a better one as its interfering with writeprocess memory and 99% of cheats use writeprocessmemory)