Require building on a tech tree

[pgp1988]

It's my first modding on R2TW. I'm using PFM 3.5 and I wanna establish a buildings requires on tech tree. Even changing the column "buildin_level" on "technology_tables/technologies", does not work. I see a unused "technologies_required_building_levels_junctions_tables", but only have a one column named "unused". How can I do? Is not possible establish required buildings on tech tree?

Thanks!