Occluder 100% occlude:)

[Creep]

Now in my new map there is 5 parts, and I wanna use occluder texture to hide em, and you can see only that where you are. But sometimes it's works with 100% sucess, sometimes it's occlude only a bit from the other part and it's ugly :S So somebody know how can I make 100% occluding with this or other texture?:)