Why am I only allowed to trigger my dash script once?

I have a player movement controller script and a dash script. The movement controller turns on the dash script whenever space is pressed but for some reason it only works once. It won't let me do it a second time. Can anyone tell me why?

Here's the movement controller:

 #pragma strict
 
 var originalMoveSpeed : float;
 var moveSpeed : float;
 var dashSpeed : float;
 var clampRadius : float;
 var walkSpeed : float;
 var isDashing : boolean;
 var rb2D : Rigidbody2D;
 var movement : Vector2;
 var playerObject : GameObject;
 
 function Update () {
     
     movement.x = Input.GetAxisRaw("Horizontal");
     movement.y = Input.GetAxisRaw("Vertical");
     
 }
 
 function FixedUpdate () {
     
     //normalize movement
     if (movement.magnitude > 1) {
         movement = movement.normalized;
     }
     
     //move
     rb2D.MovePosition(rb2D.position + movement * moveSpeed * Time.fixedDeltaTime);
     movement = Vector3.ClampMagnitude(movement, clampRadius);
     
     //dash
     if(Input.GetKeyDown(KeyCode.Space) && playerObject.GetComponent(playerDash).enabled == false) {
         playerObject.GetComponent(playerDash).enabled = true;
     }
     //walk
     if(Input.GetKey(KeyCode.LeftShift) == true && !Input.GetKeyDown(KeyCode.Space) == true) {
         moveSpeed = walkSpeed;
     }
     else {
         moveSpeed = originalMoveSpeed;
     }
     
     
 }
 

Here's the dash script:

 #pragma strict
 
 var dashSpeed : float;
 var dashTime : float;
 var isDashing : boolean;
 var playerObject : GameObject;
 
 function Start () {
     isDashing = true;
     playerObject = GameObject.Find("player");
     yield WaitForSeconds(dashTime);
     isDashing = false;
 }
 
 function Update () {
     
     if(isDashing == true) {
         playerObject.GetComponent(playerMovement).moveSpeed = dashSpeed;
     }
     
     else {
         playerObject.GetComponent(playerMovement).moveSpeed = playerObject.GetComponent(playerMovement).originalMoveSpeed;
         playerObject.GetComponent(playerDash).enabled = false;
     }
 }