So when I try to create a mod that adds various laws but when I try making a law that gives you a bonus to equipment cost for some resaosn it dosenot seem to work

equipment_bonus = {
support_equipment = {
build_cost_ic = -0.25
}
}

but when I put this in it says I have the bonus but dosenot apply it when it is applied the equipmen cost is 0.50 but dsoe not change if someone knows how to fix this please help.