OverlapSphere not detecting colliders in range so AddExplosionForce can't work properly

I have a car prefab with a Rigidbody component attached to it (root element), the colliders (box colliders) are child of Chassis (child of root) something like this: Car/Chassis/Colliders. When I fire a rocket with a script attached using Physics.OverlapSphere it won't detect the colliders nor Rigidbody in the car. Any suggestion?

Here is the script attached to the rocket....

 #pragma strict
 
 var radius :float = 5;
 var power : float = 10;
 var explosiveLift : float = 1.0;
 var explosion : GameObject;
 var explSound : AudioClip;
 
 `enter code here`function Start () {
     Destroy(gameObject, 3);
 }
 
 function OnCollisionEnter (collision : Collision) {
     var grenadeOrigin : Vector3 = transform.position;
     var colliders : Collider[] = Physics.OverlapSphere(grenadeOrigin, radius);
 
     for (var hit : Collider in colliders){
         if (hit.GetComponent.<Rigidbody>()){
             hit.transform.GetComponent.<Rigidbody>().AddExplosionForce(power, grenadeOrigin, radius, explosiveLift);
             Debug.Log("Rigidbodies in area " + hit.GetComponent.<Rigidbody>().gameObject.name);
                  var explosion1 : GameObject;
              explosion1 = Instantiate(explosion, transform.position, transform.rotation);
              GetComponent.<AudioSource>().Play();
 
 
             Destroy(gameObject);
             Destroy(explosion1, 3);
         }else {Debug.Log("No Rigidbodies in range");}
     } 
 }

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