Animation transitions are not always triggered with state change

I have a simple character controller script w$$anonymous$$ch I use to use WASD to move a character forward, backward and side to side. I then have an animation script that takes the WASD button presses and declares an animation state (0 = idle, 1-4 = up,down,left,right) w$$anonymous$$ch then triggers animations related to those directions.

T$$anonymous$$s works, but often the character animations will transition to idle instead of going to the transition that the state change should dictate.

What do you t$$anonymous$$nk is going wrong to create t$$anonymous$$s inconsistency? Scripts and screenshots below.

Player Movement Script

 using UnityEngine;
 using System.Collections;
 
 public class playerMobility : MonoBehaviour {
 
     public float speed;
 
     private Rigidbody2D rb2d;
 
     void Start()
     {
         rb2d = GetComponent<Rigidbody2D> ();
     }
     void FixedUpdate()
     {
         float moveHorizontal = Input.GetAxis ("Horizontal");
         float moveVertical = Input.GetAxis ("Vertical");
         Vector2 movement = new Vector2 (moveHorizontal, moveVertical);
         rb2d.AddForce (movement * speed);    
     }
 
 
 }

Player Animation Script

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class playerManager : MonoBehaviour {
 
 
     Animator anim;
 
     // Use t$$anonymous$$s for initialization
     void Start () 
     {
         anim = GetComponent<Animator> ();
     }
     
     // Update is called once per frame
     void Update () 
     {
         if (Input.GetKeyDown (KeyCode.W)) {
             anim.SetInteger("State",4);
         } 
 
         if (Input.GetKeyUp (KeyCode.W)) {
             anim.SetInteger("State",0);
         } 
 
         if (Input.GetKeyDown (KeyCode.S)) {
             anim.SetInteger ("State",1);
         } 
 
         if (Input.GetKeyUp (KeyCode.S)) {
             anim.SetInteger ("State",0);
         } 
 
         if (Input.GetKeyDown (KeyCode.D)) {
             anim.SetInteger ("State",3);
         } 
 
         if (Input.GetKeyUp (KeyCode.D)) {
             anim.SetInteger ("State",0);
         } 
 
         if (Input.GetKeyDown (KeyCode.A)) {
             anim.SetInteger ("State", 2);
         }
 
         if (Input.GetKeyUp (KeyCode.A)) {
             anim.SetInteger ("State", 0);
         } 
     }
 }
 

Animator screenshot

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