How to disable Age advance

[Thrust123]

I am making some colonnial era scenarios.
The scenario will cover ages: Middle to age of enlightment, but i want one of the sides to not be able to reach the enlightment age, only the gunpowder age.

I have created a script putting the following in the "run once" part:
disable_tech(4, "enlightenment");

which didn't work.
Then I tried:

disable_tech(4,"Levee en Massee");

Which In figured would not let player 4 reach the enlightment age because for that you need that "Levee en Massee" technology.
But this is not working either.

Does anyone have a better idea?

Byt the way, the player is green coloured, that's why I use "4" to identify it as per the manual.

[One_Dead_Villy]

another way is if u are willing to mod the game...just set all the tribe masks for the techs u want to 0 to disable them in techrules.xml