my idle animation isnt transitioning to its run animation

this is the code im using

using UnityEngine;
 using System.Collections;
 
 public class MainCharCtrl : MonoBehaviour 
 {
     public float maxSpeed = 10f;
     bool facingRight = true;
 
     Animator anim;
 
     void Start () 
     {
         anim = GetComponent<Animator> ();
     }
     
     void FixedUpdate () 
     {
         float move = Input.GetAxis ("Horizontal");
 
         anim.SetFloat ("Speed", Mathf.Abs (move));
         
         rigidbody2D.velocity = new Vector2 (move * maxSpeed, rigidbody2D.velocity.y);
         
         if(move > 0 &&!facingRight)
             Flip ();
         else if (move < 0 && facingRight)
             Flip ();
     }
     
     void Flip()
     {
         facingRight = !facingRight;
         Vector3 theScale = transform.localScale;
         theScale.x *= -1;
         transform.localScale = theScale;
     }
 }

ive already made transitions in the animator and set them but its not working, though it was working just fine earlier on

have you attached the animation controller to the object from the inspector?

the code looks like it should be working.