(civilization IV) " fast production" cheat is not working

I am playing civilization IV using infinity.Yesterday i downloaded and installed the game and all cheats worked perfectly.Today I loaded the saved game, but the " fast production" cheat is not working.I tried everything i could.
I start the actual gameplay and than i start the cheat, as i sholud do.If you have any idea of what should i do please tell me.For further questions just ask.Thank you.