What's wrong with this code

Questions & Answers
1

I asked this question earlier in the comments of another question of mine, but it was closed. What’s wrong with this code? It doesn’t run. I don’t know why. Can you please help? By the way I’m new to programming so I’m sorry if it’s painfully obvious.
Other Question

 public List<string> PlayerList = new List<string>();
     
     public bool offlineMode = false;
 
     Dictionary<string, GameObject> PlayerDictionary = new Dictionary<string, GameObject>();
     
     public static void RegisterPlayerObject (string playerName, GameObject playerGameObject) {
         NetworkManager nm = GameObject.Find("Manager").GetComponent<NetworkManager>();
         nm.PlayerDictionary.Add (playerName, playerGameObject);
         nm.PlayerList.Add(playerName);
     }
 
     void OnPhotonPlayerConnected(){
         if (!PlayerList.Contains (PhotonNetwork.playerName)) {
             PlayerList.Add (PhotonNetwork.playerName);
         }
     }
     void TagRandomPlayer(){
         int PlayerListRange = PlayerList.Count;
         System.Random Rand = new System.Random ();
         int RandomPick = Rand.Next (0, PlayerListRange);
         string TaggedPlayer = PlayerList [RandomPick];
         Knife knife = PlayerDictionary [TaggedPlayer].GetComponent<Knife>();
         ((MonoBehaviour)knife.GetComponent("Knife")).enabled = true;
     }
     IEnumerator OnNewRound(){
         yield return new WaitForSeconds(10);
         TagRandomPlayer ();
         Debug.Log ("Hello");
     }
     // Use this for initialization
     void Start () {
         spawnSpots = GameObject.FindObjectsOfType<SpawnSpot>();
         Connect ();
         OnNewRound ();
     }
2

To start with, you must use StartCoroutine(). Line 35 should be:

 StartCoroutine(OnNewRound ());