My character wont jump when on downward slope or when on the edge of object that is on?

Hello guys, the problem is when i jump on an object and i need to jump again immediately, my character just ignores the button and dosent jump, here's the scripts so if anyone can help me, thank you!

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

public class PlayerController : MonoBehaviour {

 //kretanje i skaknje
 public float brzinaKretanja;
 public float skok;
 public CharacterController controller;
 public Vector3 smjerKretanja;
 public float gravityScale;


 //Zvukovi kretanja
 public AudioSource jumpingSound;
 public AudioSource movingSound;
 public float velocity;

 //Knockback varijable
 public float knockBackForce;
 public float knockBackTime;
 private float knockBackCounter;

 //Dash varijable
 public float dashForce;
 public float dashTime;
 private float dashCounter;

 public Animator anim;
 public Color newColor;
 public bool facingRight;

 void Start () {
     Cursor.visible = false;
     controller = GetComponent<CharacterController>();
 }


 void Update() {

     if (knockBackCounter <= 0) { 
     float yStore = smjerKretanja.y;
     float zStore = smjerKretanja.z;
     smjerKretanja = (transform.forward * (Input.GetAxis("Vertical"))+(transform.right*Input.GetAxis("Horizontal")));
     smjerKretanja = smjerKretanja * brzinaKretanja;
     smjerKretanja.y = yStore;

         if (controller.isGrounded)
         {
             smjerKretanja.y = 0f;
         
          if (Input.GetButtonDown("Jump") && controller.isGrounded)
             {

             smjerKretanja.y = skok;

             }

         }

         //Onemogućavanje kretanje po Z osi
         smjerKretanja.z = zStore;

         //Dash funkcija
         if (Input.GetButtonDown("Dash") && controller.isGrounded)
         {
             Vector3 dash;
             dashCounter = dashTime;
             dash = new Vector3(5f, 0, 0);
             smjerKretanja = dash * dashForce;

         }


     }
     else
     {
         knockBackCounter -= Time.deltaTime;
         dashCounter -= Time.deltaTime;
     }

     //If za zvuk skoka
     if (Input.GetButtonDown("Jump") && controller.isGrounded){
         jumpingSound.Play();
     }

     smjerKretanja.y = smjerKretanja.y + (Physics.gravity.y * gravityScale*Time.deltaTime);
     controller.Move(smjerKretanja *Time.deltaTime);

     //Animator i animacije
     anim.SetBool("isGrounded", controller.isGrounded);
     anim.SetFloat("isMoving", (Mathf.Abs(Input.GetAxis("Vertical"))+Mathf.Abs(Input.GetAxis("Horizontal"))));

 }



 public void Knocback(Vector3 direction)
 {
     knockBackCounter = knockBackTime;
     direction = new Vector3(-0.5f, 1f, 0);
     smjerKretanja = direction * knockBackForce;

 }