Question Unable to transition to other animations on my Character Controller

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4.  
5. public class PlayerMovement : MonoBehaviour
6. {
7.     //VAR
8.     [SerializeField] private float moveSpeed;
9.     [SerializeField] private float walkSpeed;
10.     [SerializeField] private float runSpeed;
11.  
12.     private Vector3 moveDirection;
13.     private Vector3 velocity;
14.  
15.     [SerializeField] private bool isGrounded;
16.     [SerializeField] private float groundCheckDistance;
17.     [SerializeField] private LayerMask groundMask;
18.     [SerializeField] private float gravity;
19.  
20.     [SerializeField] private float jumpHeight;
21.  
22.     //REF
23.     private CharacterController controller;
24.     private Animator anim;
25.  
26.     private void Start()
27.     {
28.         controller = GetComponent<CharacterController>();
29.         anim = GetComponentInChildren<Animator>();
30.     }
31.  
32.     private void Update()
33.     {
34.         Move();
35.     }
36.  
37.     private void Move()
38.     {
39.         isGrounded = Physics.CheckSphere(transform.position, groundCheckDistance, groundMask);
40.  
41.         if(isGrounded && velocity.y < 0)
42.         {
43.             velocity.y = -2f;
44.         }
45.  
46.         float moveZ = Input.GetAxis("Vertical");
47.  
48.         moveDirection = new Vector3(0, 0, moveZ);
49.         moveDirection = transform.TransformDirection(moveDirection);
50.  
51.         if(isGrounded)
52.         {
53.             if (moveDirection != Vector3.zero && !Input.GetKey(KeyCode.LeftShift))
54.             {
55.                 Walk();
56.             }
57.             else if (moveDirection != Vector3.zero && Input.GetKey(KeyCode.LeftShift))
58.             {
59.                 Run();
60.             }
61.             else if (moveDirection == Vector3.zero)
62.             {
63.                 Idle();
64.             }
65.  
66.             moveDirection *= moveSpeed;
67.  
68.             if (Input.GetKeyDown(KeyCode.Space))
69.             {
70.                 Jump();
71.             }
72.         }
73.  
74.      
75.  
76.         controller.Move(moveDirection * Time.deltaTime);
77.  
78.         velocity.y += gravity * Time.deltaTime;
79.         controller.Move(velocity * Time.deltaTime);
80.     }
81.  
82.     private void Idle()
83.     {
84.         anim.SetFloat("Speed", 0);
85.     }
86.  
87.     private void Walk()
88.     {
89.         moveSpeed = walkSpeed;
90.         anim.SetFloat("Speed", 0.5f);
91.     }
92.  
93.     private void Run()
94.     {
95.         moveSpeed = runSpeed;
96.         anim.SetFloat("Speed", 1);
97.     }
98.  
99.     private void Jump()
100.     {
101.         velocity.y = Mathf.Sqrt(jumpHeight * -2 * gravity);
102.     }
103. }
104.  

I trying to get my character shift from an idle cycle to a walking/running cycle but I don't know why it isn't working. It kept prompting:

Parameter 'Speed' does not exist.
UnityEngine.Animator:SetFloat (string,single)
PlayerMovement:Idle () (at Assets/Script/PlayerMovement.cs:84)
PlayerMovement:Move () (at Assets/Script/PlayerMovement.cs:63)
PlayerMovement:Update () (at Assets/Script/PlayerMovement.cs:34)

Could someone help me please!