unity playmaker 问题

为什么这个action是灰色的，没有执行呀，没有报错

namespace HutongGames.PlayMaker.Actions
{
    public class IsHud: FsmStateAction
    {
        public FsmEvent NextEvent;

        public override void OnUpdate()
        {
            base.OnUpdate();
            if (PlayerManager.Instance.isHud)
            {
                Fsm.Event(NextEvent);
            }
        }
    }
}

using UnityEngine;

namespace HutongGames.PlayMaker.Actions
{
    public class DoubleHandPrepear: FsmStateAction
    {
        public FsmEvent NextEvent;

        public override void OnEnter()
        {
            base.OnEnter();
        }

        public override void OnUpdate()
        {
            base.OnUpdate();
            Fsm.Event(NextEvent);
        }
    }
}