Box Collider 2D not triggering

I have 2 gameobjects with Box Collider 2D components. One of those gameobject moves around but they start off intersected. That gameobject that moves has the Is Trigger set on the Box Collider 2D, it also has a script attached that looks as follows:

public class ShooterColliderController : MonoBehaviour {

	public ShooterController controller;
	
	void OnTriggerExit2D( Collider2D otherObj )
	{
		Debug.Log ("Exit");
	}
}

That OnTriggerExit2D method is never called when the game is running. What have I done wrong? What other information can I give to help debug this?

http://docs.unity3d.com/Documentation/Components/class-BoxCollider.html

“If you are moving an object through its Transform component but you want to receive Collision/Trigger messages, you must attach a Rigidbody to the object that is moving.”

basically its all about physics, if you want to always remember it , just think of it this way.
a BoxCollider is like a spirit , it needs a body so that you can interact with it :smiley:

this way you will never forget it :smiley:
cheers!

Wow that took a while to figure out. The second object that moves around needs a Rigidbody 2D component. Can anyone tell me why that is?