Crouching makes my player unable to move.

So I am trying to make my character crouch. However it stops the ability to move all together. Can anyone figure out why.

 if (isStanding == true) {
             float forwardSpeed = Input.GetAxis ("Vertical") * movementSpeed;
             float sideSpeed = Input.GetAxis ("Horizontal") * movementSpeed;
 
             // Determine movement speed in every direction
             
             Vector3 speed = new Vector3 (sideSpeed, verticalVelocity, forwardSpeed);    
             speed = transform.rotation * speed;
             characterController.Move (speed * Time.deltaTime);
         }
 
         //Crouching
         if (Input.GetKeyDown(KeyCode.C) && characterController.isGrounded)
         {
             // Determine movement speed in every direction
 
             float forwardSpeed = Input.GetAxis ("Vertical") * crouchingSpeed;
             float sideSpeed = Input.GetAxis ("Horizontal") * crouchingSpeed;
 
             Vector3 speed = new Vector3 (sideSpeed, verticalVelocity, forwardSpeed);    
             speed = transform.rotation * speed;
             characterController.Move (speed * Time.deltaTime);
 
             Crouch (forwardSpeed,sideSpeed);
         }
 
 public void Crouch(float forwardSpeed, float sideSpeed) {
         if (!isCrouching) //Crouch
         {
             isCrouching = true;
             isProne = false;
             isStanding = false;
             characterController.height = crouchHeight;

             
             //        characterController.center = Vector3(0, -0.5, 0);
             //        tempCamera.transform.localPosition.y -= crouchHeight;
         }
         else //Stand back up
         {
             isCrouching = false;
             characterController.height = charHeight;
             isStanding = true;
             isProne = false;
             //        characterController.center = Vector3(0, 0, 0);
             //        tempCamera.transform.localPosition.y += crouchHeight;
             
         }
     }