[UNET] Can't spawn players with code

Hi,
i am using Server-Side code.I am making a storyline co-op game.So, because of that i can’t use networkmanager’s auto player spawn system.I am trying to spawn player from server-side storyline code but it’s not working.Ever, when i am trying that script that on SERVER it’s not giving player permission to player prefab.

To Spawn :

GameObject player = (GameObject)Instantiate(playerObject, Vector3.zero, Quaternion.identity);
            NetworkServer.AddPlayerForConnection(conn, playerObject, 0); 

To Call that :

SpawnPlayers(connectionToServer);

Please help me, thanks!

Omg, Can any one help please?!