Box Collider Trigger never being triggered.

So I have a circle collider with a rigid body passing through an invisible box collider that is set as a trigger. I have written a simple script for the invisible 2D box collider with the following function

     void OnTriggerEnter(Collider other){
         Debug.Log ("Triggered by: " + other.name);
     }

The problem is that this function is never called when the ridgidbody passes through the trigger box collider. How can I make this function log the message to the console?

Any help is appreciated, thanks.