onMouseUp 2D Issues

This seems to be a common issue with 2D colliders, but onMouseUp() isn't working at all. I've tested it with a Collider2D, a 3D Collider, an orthographic camera and a perspective camera, I've created code to make sure raycast hits the object (it does). I have the object in the scene with the script attached to it that has the void onMouseUp() function. I've also heard that moving the object closer to the camera helps, but it doesn't. There's nothing between the camera and the object.

 public Collider coll;
     void Start() {
         coll = GetComponent<Collider>();
     }
     void Update() {
         if (Input.GetMouseButtonDown (0)) {
             Ray ray = Camera.main.ScreenPointToRay (Input.mousePosition);
             RaycastHit hit;
             if (coll.Raycast (ray, out hit, 100.0F)){
                 transform.position = ray.GetPoint (100.0F);
             }
             Debug.Log("hey");
         }
     }
 
     void onMouseOver(){
         if(Input.GetMouseButtonUp(0)){
             Debug.Log("yo");
         }
     }
 
     public void onMouseUp(){
         Debug.Log ("hi");
     }

These are the functions I have running on my object. Commenting out any combination of them doesn't solve the problem.