Animation dont change when it should change

Hey guys... I've got a problem...

My animation is working wrongly... when I jump, it triggers the animation "rise" fine, and also starts falling well when the velocity in y axis is less than 0, BUT

when the player touches the ground (that means its y velocity is 0), the "fall" animation keeps on playing for a while before it triggers "walk"... he kind of keeps falling even thou he is already grounded, and just about 1 second later that he starts walking (the bool values "falling" and "jumping" also stay true while he is already on the ground and only later they go false).

what am I doing wrong? My code is down below... y() is a function that returns transform.rigidbody2D.velocity.y

 public Transform ninja;
 public Animator anim;
 public bool jumping, rising, falling, grounded; 
 
 void Start () {
     anim = ninja.GetComponent<Animator> ();
     jumping = rising = grounded = false;
     falling = true;
 }
 
 void Update () {
     StateControl ();
     ButtonControl ();
 }
 
 void StateControl(){
     if (y () > 0 && grounded && jumping) {
         anim.SetTrigger("rise");
         grounded = false;
         rising = true;
     }
     if(y () < 0 && rising){
         anim.SetTrigger("fall");
         rising = false;
         falling = true;
     }
     if(y () == 0 && falling){
         anim.SetTrigger("walk");
         falling = false;
         grounded = true;
         jumping = false;
     }
 }
 
 void ButtonControl(){
     if (Input.GetKeyDown ("d") && grounded && !jumping) {
         transform.rigidbody2D.AddForce(new Vector2(0, 50));
         jumping = true;
     }
 }