Here is my script. 
using FishNet.Object;
using FishNet.Object.Synchronizing;
using FishNet.Transporting;
using System.Collections;
using UnityEngine;
using HutongGames.PlayMaker;
namespace Client.Health
{
    public class ClientHealth : NetworkBehaviour
    {
        [SyncVar(Channel = Channel.Unreliable, ReadPermissions = ReadPermission.Observers, SendRate = 0.1f, OnChange = nameof(OnServerHealth))]
        private float ServerHealth;
        public float LocalHealth;
        private void OnServerHealth(float prev, float next, bool asServer)
        {
            if (!asServer)
                LocalHealth = ServerHealth;
            else
                Debug.Log($"New health value: {next}.");
        }
    }
}
I keep getting this error: [TargetParameterCountException: Number of parameters specified does not match the expected number]
I am trying to use Set Property on the script to get the private float, ServerHealth but it just doesnt work. What am I doing wrong?