Making an AI Assault

No matter what I try, I just cannot get the combines to assault where I tell them to. I have even tried using a prefab hl2 combine assault that came with hammer, but still the combine just stand there. What I want to do is make it to where combine spawn and try to take over your base, sorta like combine onslaught except on mine, once they get in your base, and destroy the target, then you lose. Any ideas one how to make my combines head towards the target?

Have you read this: http://www.snarkpit.com/editing.php?page=tutorials&game=HL2&id=144

yes,yes i have, and it did not help me. word for word