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