Problem with a multi-jump script ( C# )

As the title says, i have a problem with a script that should allow me make a multi-jump with a JumpCount wich is going to run out after 4 jumps and recharge when i touch the ground. The script does not give any error, but i think there is something wrong directly in the script's drawing up It simply doesen't work when i apply it, my character jumps just one time.

 using UnityEngine;
 using System.Collections;
 
 public class Volo : MonoBehaviour {
     float jumpCount;
     public Vector2 jumpForce = new Vector2(0, 300);
     bool grounded;
     void Update()
     {
         // If the character has more than 0 jumps left
         if (Input. GetKeyDown("space") && jumpCount > 0)
         {
             GetComponent<Rigidbody2D>().velocity = Vector2.zero;
             GetComponent<Rigidbody2D>().AddForce(jumpForce);
             jumpCount--; // Reduce the amount of jumps left by 1
         }
         // If the character is touching the ground
         if (grounded)
         {
             jumpCount = 4; // Reset amount of jumps left to 4
         }
     }
     
     void OnCollisionEnter(Collision col) // When the character collides with something
     {
         if(col.collider.tag == "ground") // If the object has the tag "ground"
         {
             grounded = true;
         }
     }
     void OnCollisionExit(Collision col) // When the character stops colliding with something
     {
         if(col.collider.tag == "ground") // If the object has the tag "ground"
         {
             grounded = false;
         }
     }
 }