The player ball only jumps only when is not in motion

How do I make the ball jump also when the ball is in motion or in movement ? how i can fix this script ?

#pragma strict
     var jumpObject : Rigidbody;
     var jumpDelay : boolean;
     var canJump : boolean;
     var groundTag : String = "Ground";
     var jumpHeight = 10.0;
     var doublejumpHeight = 7.5;
     private var doubleJump : boolean;
     
     function OnCollisionEnter(col: Collision) {
     if(col.collider.tag == groundTag) {
     doubleJump = false;
     canJump = true;
     }
     }
     
     function OnCollisionExit(col: Collision) {
     if(col.collider.tag == groundTag) {
     canJump = false;
     }
     }
     
     function Update () {
     if(canJump == true && Input.GetKeyDown(KeyCode.Space)) {
     jumpObject.velocity.y = jumpHeight;
     doubleJump = true;
     }
     if(canJump == false && doubleJump == true && Input.GetKeyDown(KeyCode.Space)) {
     jumpObject.velocity.y = doublejumpHeight;
     doubleJump = false;
     }
     }

Try swapping both these lines :

if(col.collider.tag == groundTag) {

to this :

if (col.gameObject.tag == groundTag) {