Pushing Nearby Objects Directly Away

Here's what I'm trying to do.

Thematically, I'm trying to get a force pulsing outward from the player that grows to its max size, applying a force to any object it comes into contact with while it's growing.

I'm currently trying to do this by having a button press instantiate a game object with a capsule collider and the following script.

Code (csharp):

1.  
2. var maxSize         : float = 2.0;
3. var growthRate      : float = 2.0;
4. var scale           : float = 0.1;
5.  
6. var atMaxSize       : boolean = true;
7.  
8. function Update ()
9. {
10.     if (atMaxSize == true)
11.     {
12.         collider.radius = scale;
13.         scale += growthRate * Time.deltaTime;
14.         if(scale > maxSize) atMaxSize = false;
15.        
16.     }
17.     else if (atMaxSize == false)
18.     {
19.         Destroy(gameObject);
20.     }
21. }
22.  
23. function OnTriggerEnter (other : Collider)
24. {
25.    
26.     if(other.tag == "block")
27.     {
28.         print("Object hit");
29.         other.rigidbody.AddForce(Vector3(other.transform.position.x - transform.position.x, 0, other.transform.position.y - transform.position.y) * 1500);
30.     }
31. }
32.    
33.  
34.  

So far, the object is instaniated in scene to the player's position by a different script. Then this script causes the object's capsule collider to grow until it reaches a radius of 2 and then is destroyed.

What is getting me is that sometimes the print("Object hit") fires, and even less consistently will a force be added to the other collider.

Is it possible that the radius of the collider grows past another object and so never catchs the onTriggerEnter call?

How can I get this to consistently apply force on other colliders directly away form this object as it's collider grows into them?

Thanks for looking!