Problem with Boolean

Hello, so I am working on my first game. It is a third person not-yet-shooter. The most recent feature I added was a health bar "borrowed" from Brackeys. I also wanted to make a stamina bar, but it is not working. I have a script named "ThirdPersonMovement" and "AdvanceMovement" and "HealthBarScript".

 public class HealthBarScript : MonoBehaviour
 {
     public Slider healthBar;
     public Slider staminaBar;
     public Gradient gradientHealth;
     public Gradient gradientStamina;
     public Image fill;
 
     public void SetMaxHealth(int health)
     {
         healthBar.maxValue = health;
         healthBar.value = health;
 
         fill.color = gradientHealth.Evaluate(1f);
     }
 
     public void SetHealth(int health)
     {
         healthBar.value = health;
 
         fill.color = gradientHealth.Evaluate(healthBar.normalizedValue);
     }
 
     public void SetMaxStamina(int stamina)
     {
         staminaBar.maxValue = stamina;
         staminaBar.value = stamina;
 
         fill.color = gradientStamina.Evaluate(1f);
     }
 
     public void SetStamina(int stamina)
     {
         staminaBar.value = stamina;
 
         fill.color = gradientStamina.Evaluate(healthBar.normalizedValue);
     }
 }
 
 
 
 public class AdvanceMovement : MonoBehaviour
 {
     ThirdPersonMovement basicMovementScript;
     public float speedBoost = 10f;
     public bool isSprinting;
 
     // Start is called before the first frame update
     void Start()
     {
         basicMovementScript = GetComponent<ThirdPersonMovement>();
     }
 
     // Update is called once per frame
     void Update()
     {
         if(Input.GetKeyDown(KeyCode.LeftShift) && isSprinting == false)
         {
             basicMovementScript.speed += speedBoost;
             isSprinting = true;
         }
         else if (Input.GetKeyDown(KeyCode.LeftShift) && isSprinting == true)
         {
             basicMovementScript.speed -= speedBoost;
             isSprinting = false;
         }
     }   
 
 
 }
 
 

using System.Collections; using System.Collections.Generic; using UnityEngine;

public class ThirdPersonMovement : MonoBehaviour { public AdvanceMovement isSprinting; AdvanceMovement advanceMovementScript;

 public HealthBarScript healthBar;
 public HealthBarScript staminaBar;
 public int currentHealth;
 public int maxHealth = 100;
 public int currentStamina;
 public int maxStamina = 100;

 public CharacterController controller;
 public Transform cam;

 public float speed = 6f;

 public float turnSmoothTime = 0.1f;
 float turnSmoothVelocity;

 public float gravity = -9.81f;
 public float jumpHeight = 3f;

 public Transform groundCheck;
 public float groundDistance = 0.4f;
 public LayerMask groundMask;


 Vector3 velocity;
 bool isGrounded;

 void Start()
 {
     advanceMovementScript = GetComponent<AdvanceMovement>();
     Cursor.visible = false;
     currentHealth = maxHealth;
     healthBar.SetMaxHealth(maxHealth);

     currentStamina = maxStamina;
     staminaBar.SetMaxStamina(maxStamina);


     
 }

 

 void TakeDamage(int damage)
 {
     currentHealth -= damage;

     healthBar.SetHealth(currentHealth);
 }

 void TakeStamina(int weak)
 {
     currentStamina -= weak;

     staminaBar.SetStamina(currentStamina);
 }
 
 void Update()
 {
     //Damage
     if (Input.GetKeyDown(KeyCode.K))
     {
         TakeDamage(20);
     }

     //Weak
     if (Input.GetButtonDown("Fire3") && isSprinting == false)
     {
         TakeStamina(5);
     }

     if (Input.GetButtonDown("Jump") && isGrounded)
     {
         TakeStamina(5);
     }
     // Groundcheck

     isGrounded = Physics.CheckSphere(groundCheck.position, groundDistance, groundMask);

     if(isGrounded && velocity.y < -1)
     {
         velocity.y = -2f;
     }

     // Mouselook

     float horizontal = Input.GetAxisRaw("Horizontal");
     float vertical = Input.GetAxisRaw("Vertical");
     Vector3 direction = new Vector3(horizontal, 0f, vertical).normalized;
     Cursor.lockState = CursorLockMode.Locked;

     if (direction.magnitude >= 0.1f)
     {
         float targetAngle = Mathf.Atan2(direction.x, direction.z) * Mathf.Rad2Deg + cam.eulerAngles.y;
         float angle = Mathf.SmoothDampAngle(transform.eulerAngles.y, targetAngle, ref turnSmoothVelocity, turnSmoothTime);
         transform.rotation = Quaternion.Euler(0f, angle, 0f);

         Vector3 moveDir = Quaternion.Euler(0f, targetAngle, 0f) * Vector3.forward;
         controller.Move(moveDir.normalized * speed * Time.deltaTime);

        
     }

     // Jumping

     if(Input.GetButtonDown("Jump") && isGrounded)
     {
         velocity.y = Mathf.Sqrt(jumpHeight * -2f * gravity);
     }

     velocity.y += gravity * Time.deltaTime;

     controller.Move(velocity * Time.deltaTime);




 }

} in the ThirdPersonMovement in Update() if Fire3(L Shift) & isSprinting is false, it was supposed to TakeStamina(5); Can you help me resolve this?