How to jump while gravity is reversed

My game is in Javascript. My gravity is normally -9.81 in the Y. My jumpheight is normally 9.

I've successfully flipped the gravity when my player/ball touches a special capsule. Unfortunately, I can't get the ball to jump in the opposite direction: down while I'm on the ceiling.

I have been able to change the jump height when I touch other special capsules that grow and shrink the ball (namely make the ball jump higher or lower) but I can't seem to do the above opposite jump.

Here's my code. Any ideas what I'm doing wrong? I've tried different jumpheight values. #pragma strict

 var player : GameObject;
 var gravityChangeSfx : AudioClip;
 
 
 
 var gravityC = Vector3 (0, 9.81, 0);
 
 function Awake() {
     //player = GameObject.Find("Ball").GetComponent.<Rigidbody>();
     player = GameObject.Find("Ball");
 
     Debug.Log("GravityUpsideDown script - first Find Player/Ball");
 } 
 
 
 
 
 function OnTriggerEnter (col : Collider) {
     //Trigger if only the player touched the object
     //GameObject.Find("Player"); 
     if (col.tag == "Player")  {  
             Debug.Log ("GravityUpsideDown script - ball collided with this Box");
             // Change Gravity
 
             Physics.gravity = gravityC;
 
             //Make ball jumpheight the opposite
             BallControl.jumpHeight = -9;
             Debug.Log("GravityUpsideDown script - jumpHeight made upsidedown");
 
 
             GetComponent.<AudioSource>().pitch = 1;
             GetComponent.<AudioSource>().clip = gravityChangeSfx;
             GetComponent.<AudioSource>().Play();
             Debug.Log("GravityUpsdieDown script - gravity upside down");
 
 
 
     }
     
 }

And here's my ball control code associated with the player ball:

 function Update ()
 {
 
     //Handle ball rotation.
     var rotation : float = Input.GetAxis ("Horizontal") * rotationSpeed;
     rotation *= Time.deltaTime;
     GetComponent.<Rigidbody>().AddRelativeTorque (Vector3.back * rotation);
 
     //Handle ball jump
     if (Input.GetKeyDown(KeyCode.W) && IsGrounded ())
 
 
 
     {    
         GetComponent.<Rigidbody>().velocity.y = jumpHeight; 
     }
 }
 
 function IsGrounded () : boolean { //Check if we're on the ground, return True if we are, else return Null.
     return Physics.Raycast(transform.position, -Vector3.up, distToGround + 0.1);
 }

I thought the problem had to do with the "&& IsGrounded ()" so I commented that out but it still didn't work.

TIA