Third Party Mirror: Player object is not a player

Hi guys,
when my PlayerPrefab launch this code

Code (csharp):

1. public override void OnStartLocalPlayer () {
2.         base.OnStartAuthority ();
3.         Vector3 spawnPos = _spawnPos;
4.         if (GetComponent<CameraMovement>().num == 1) spawnPos = _spawnPos + new Vector3(47, 0, 0);
5.         NetworkServer.Spawn(Instantiate(_basePrefab, spawnPos, Quaternion.identity), gameObject);
6.     }

it raises me this error:
Player object is not a player.
UnityEngine.Debug:LogError(Object)

Do you know why and what does it mean?
Thank you!

 

Take a step back and read through our documentation.
You are trying to call server functions from the client, which won't work.