hex codes (Tomb Raider: Anniversary)

Hello, here http://www.playground.ru/cheats/tomb_raider_anniversary_1_0_hex-kodi-58573/ you tell how you can change the value for the code. I am trying to change the code to get infinite time.
I can't do it, the game just won't start after changing the .exe file. Perhaps I am making some mistake. Help advice or something else. If you have an .exe file already modified, please provide it. In general, help, good people!