Network.Instantiate

Hello guys!

I wanted to explore the world of the unity networking system and I bumped into a little problem... I already got my server running and I am able to find it with my client! But as I click on the button "start new server" and want according to this I just want to spawn an object for now, my server chrashes. I don't know why but it seems that the "Network.Instantiate" is not correct? Any help plz :)

using UnityEngine; using System.Collections;

public class ServerManager : MonoBehaviour { string registeredGameName = "SC_Networkingproject_number_one_by_programmer98"; bool isRefreshing = false; float refreshRequestLenght = 3.0f; HostData[] hostData;

 private void StartServer() 
 {
     Network.InitializeServer(16, 25020, false);
     MasterServer.RegisterHost(registeredGameName, "Click Here To Join!", "Discription: test server");

 }

 void OnServerInitialized()
 {
     Debug.Log("Server has been intizialized!");
     SpawnPlayer();
 }

 void OnMasterServerEvent(MasterServerEvent masterServerEvent)
 {
     if(masterServerEvent == MasterServerEvent.RegistrationSucceeded)
     {
         Debug.Log("Registration Succsessful!");

     }
 }
 public IEnumerator RefreshHostList()
 {
 
     Debug.Log("Refreshing...");
     MasterServer.RequestHostList (registeredGameName);
     float timeStarted = Time.time;
     float timeEnd = Time.time + refreshRequestLenght;

     while (Time.time < timeEnd)
     {
         hostData = MasterServer.PollHostList();
         yield return new WaitForEndOfFrame();
     }

     if (hostData == null || hostData.Length == 0) {
         Debug.Log ("No Active Servers Have Been Found!");
     } 
     else 
     {
         Debug.Log (hostData.Length + "Found!");
     }
 }

 private void SpawnPlayer()
 {

     Debug.Log ("Spawning Player...");
     Network.Instantiate (Resources.Load("Prefabs/Cube"), new Vector3(0.0f, 2.0f,.0f), Quaternion.identity, 0);
 }
 public void OnGUI()
 {
     if (Network.isClient || Network.isServer)
     { 
         return;
     }
     if (GUI.Button (new Rect(Screen.width/2, 25, 150 ,35), "start new server"))
     {
         //Start server function here:
         StartServer();
         Debug.Log("Connecting...!");

     }
     if (GUI.Button (new Rect(Screen.width/2, 65, 150, 35), "Refresh server list"))
     {
         //Refresh server function here:
         StartCoroutine("RefreshHostList");
     }
     if (hostData != null)
     {
         for (int i = 0; i < hostData.Length; i++)
         {    
             if (GUI.Button (new Rect(Screen.width/2, 65+(30 * i), 300, 35), hostData[i].gameName))
             {
                 Network.Connect(hostData[i]);
             }
         }
     }
 }

}

Script source (https://www.youtube.com/watch?v=BRAcRGhcMKc) by CodeCompile