GetButtonDown not registering?

Whenever my character is on the ground sometimes space doesn't make him jump. I'm making a movement script with a double jump.

 using UnityEngine;
 
 public class PlayerControls : MonoBehaviour
 {
     public float gravity;
     public float jumpforce;
     public float speed;
     public CharacterController cc;
     public float verticalvelocity;
     private Vector3 velocity;
     public int jumps = 0;
     public int maxJumps = 2;
     // Update is called once per frame
     void Update()
     {
         Move();
 
         if (jumps < maxJumps && Input.GetButtonDown("Jump"))
         {
             verticalvelocity = jumpforce;
             jumps += 1;
         }
     }
 
     void Move()
     {
         float Xmove = Input.GetAxisRaw("Horizontal");
         float Zmove = Input.GetAxisRaw("Vertical");
 
         Vector3 movehorizontal = transform.right * Xmove;
         Vector3 movevertical = transform.forward * Zmove;
 
         velocity = (movehorizontal + movevertical).normalized * speed * Time.deltaTime;
 
         ApplyGravity();
         cc.Move(velocity);
     }
 
     void ApplyGravity()
     {
         if  (cc.isGrounded)
         {
             jumps = 0;
             verticalvelocity = 0f;
 
         } else
         {
             verticalvelocity -= gravity * Time.deltaTime;
         }
 
         velocity.y = verticalvelocity * Time.deltaTime;
     }
 }