building maintenance reduction Trait for Wonder. Problem

[duckhangvo1998]

Hi I am trying to add Building maintenance reduction trait to a custome wonder.

Anyways there a policy from Vanila in the "order" branch that give you 15% maintance reduction for building. So I add this trait " <BuildingGoldMaintenanceMod>-15</BuildingGoldMaintenanceMod>" in the building.xml like this

<?xml version="1.0" encoding="utf-8"?>
<GameData>
<Buildings>
<Row>
<Type>BUILDING_PETRONAS</Type>
<BuildingClass>BUILDINGCLASS_PETRONAS</BuildingClass>
<Description>TXT_KEY_BUILDING_PETRONAS</Description>
<Help>TXT_KEY_WONDER_PETRONAS_HELP</Help>
<Civilopedia>TXT_KEY_WONDER_PETRONAS_PEDIA</Civilopedia>
<Quote>TXT_KEY_WONDER_PETRONAS_QUOTE</Quote>
<Cost>1250</Cost>
<PrereqTech>TECH_GLOBALIZATION</PrereqTech>
<MaxStartEra>ERA_FUTURE</MaxStartEra>
<SpecialistType>SPECIALIST_MERCHANT</SpecialistType>
<GreatPeopleRateChange>1</GreatPeopleRateChange>
<NukeImmune>true</NukeImmune>
<HurryCostModifier>-1</HurryCostModifier>
<MinAreaSize>-1</MinAreaSize>
<ConquestProb>100</ConquestProb>
<IconAtlas>BW_ATLAS_PETRONAS</IconAtlas>
<PortraitIndex>0</PortraitIndex>
<WonderSplashImage>PETRONAS_splash.dds</WonderSplashImage>
<WonderSplashAnchor>L,B</WonderSplashAnchor>
<BuildingGoldMaintenanceMod>-15</BuildingGoldMaintenanceMod>
</Row>
</Buildings>
</GameData>

well it doesnt work, building doesnt even show up in a list to build ( it does show up before I added this trait).

Another Wonder I tried to add a trait from religion which makes you receive 50 Faith everytime a great person is expended, but the wonder disappeared from the building list too. Uhrr.

Do the trait from policies and religion not working with Building ? I tried to add policies and religion traits to CIV UA and it works though.

Is there anyways I can make this work ? Can I make a building thats give a hidden Policy then using this hidden Policy to achieve this trait ? I play BNW, not Vanilla.

Thanks