Anti-block with a Tower Defense help

Hi, I have a problem with creeps running through my TD and blocking. Heres the deal, I've read that enemies, when orderless, are supposed to attack by default. This seems partially true in my case. Player 10 takes the spot of my creeps, while everyone else is a "tower defender". When I start the game, and create a wall of towers to block off the creeps from reaching their destination, the creeps will come up to the wall, and stop. This is true when player 10 (the creeps) are a "computer", "neutral", and "none" slot in the player properties. However, when I took off "Fixed player settings", I created a wall that blocked the creeps for player 1. I then took the spot of player 10 and put a computer on player 1. The game started as normal, and the creeps began their trip to their destination, but this time they instantly attacked player 1's towers and finished their way to the end. I am clueless as to why they wont attack a "blocker" when they don't have a physical person in their respective slot. Any insight on the problem would be greatly appreciated.

Ummm, agressioness against players for this might have to be triggered

-Av3n

How though? ;) I am looking on how to attack blockers as well.