How do I make a player collide with only one object?(Solved)

I have a wall, player, and a barrier. They all have collision detectors, but I only want the player to stop at the wall but he stops at the barrier also. the barrier needs the collision detector to detect the enemies so he can block them. How do I make this happen?
If it helps here is my character script

>     var speed = 3.0;
>     var rotateSpeed = 3.0;
>      
>     function Update ()
>     {
>             var controller : CharacterController =
> GetComponent(CharacterController);
>            
>             // Rotate around y - axis
>             transform.Rotate(0, Input.GetAxis("Horizontal") *
> rotateSpeed, 0);
>            
>             // Move forward / backward
>             var forward = transform.TransformDirection(Vector3.forward);
>             var curSpeed = speed * Input.GetAxis("Vertical");
>             controller.SimpleMove(forward *
> curSpeed);
>     }

Try using collision layers: