How do you change the breakforce and break torque of a joint through script.

I am attaching an object through collision by creating a fixed joint. I am able to add the connecting body and toggle preproccesing and collision. But I cannot change the breakforce and torque.

void OnTriggerEnter (Collider other) {

         if (other.tag == "Throw") {
         gameObject.AddComponent<FixedJoint>();
         theJoint = gameObject.GetComponent<FixedJoint>();
             theJoint.connectedBody = player.GetComponent<Rigidbody>();//player is the object I am picking up
         theJoint.enableCollision = false;
         theJoint.enablePreprocessing = false;
                     theJoint.breakForce = 0.001f;
         theJoint.breakTorque = 0.001f;
         JointGood = true;

} }

When I remove the breakforce and breaktorque lines the script will work .Any help would be appreciated.

Thanks in advance.