animation stuck at first frame and won't play

For some reason, my attack animation goes to the first frame but won't play.
here are enemy script, i'm not sure what i did wrong

extends KinematicBody2D

var speed : int = 70
var jump_speed : int = 400
var gravity : int = 1500
var velocity = Vector2()
var facing_right = true
var running
var damage = 3

onready var player = get_parent().get_node("Player")

func _physics_process(delta):
	if running:
		$Pivot/AnimationPlayer.play("Run")
	if !running:
		$Pivot/AnimationPlayer.play("Idle")
	
	if facing_right == true:
		$Pivot.scale.x = 1
	else:
		$Pivot.scale.x = -1
	
	if is_in_range() && is_on_floor():
		$Pivot/AnimationPlayer.play("Attack")
	
	calculate_velocity(delta)

func calculate_velocity(delta):
	velocity.x = 0
	
	if player.get_node("CollisionShape2D").global_position.x < $CollisionShape2D.global_position.x - 22:
		velocity.x -= speed
		facing_right = false
		running = true
	elif player.get_node("CollisionShape2D").global_position.x > $CollisionShape2D.global_position.x + 22:
		velocity.x += speed
		facing_right = true
		running = true
	else:
		velocity.x = 0
		running = false
	

	#Gravity
	velocity.y += gravity * delta
	velocity = move_and_slide(velocity, Vector2.UP)
	pass

func damage():
	if is_in_range():
		player.take_damage(damage)


func is_in_range() -> bool:
	var in_range
	var o_bodies = $Pivot/HitRange.get_overlapping_bodies()
	
	for body in o_bodies:
		if body.name == player.name:
			in_range = true
			break
		else:
			in_range = false
	
	return in_range