Mod world Generation doesn't work for servers

[ant7735]

if GLOBAL.terrain.rooms.BGSavanna then
    GLOBAL.terrain.rooms.BGSavanna.contents.distributeprefabs.hole = 0.2
end

GLOBAL.terrain.filter.hole = {GLOBAL.GROUND.ROAD, GLOBAL.GROUND.WOODFLOOR, GLOBAL.GROUND.CARPET, GLOBAL.GROUND.CHECKER, GLOBAL.GROUND.ROCKY}

This is the code I have in modworldgenmain.lua when trying it on a local game it appears, however when playing with caves it doesn't appear?