Terrain Editing Script

	local pos2 = pos + Vector3.new(4,0,4)
	local region = Region3.new(pos, pos2)
	region = region:ExpandToGrid(4)
	game.Workspace.Terrain:FillRegion(region, 4, Enum.Material.Air)

My issue is that that the side terrain erodes, but the ground doesn’t. Its probably something to do with the first line, but I’ve tried everything to make it work. I would appreciate any help at all.