How to change level after my game over screen appears? C#

Hello, I am creating game with use of a master script. Inside my Game Over Script I would like for the first level to be loaded Blank number of seconds after the Game Over Panel is set to true. When I try this my "void TurnOnGameOverPanel()" gives and error "cannot be an iterator block because `void' is not an iterator interface type". Can anyone help me out on this one? Thanks

P.S. I know my script is correct but it's my best shot at it and I'd stuck. It's in C# by the way. :)

  public class GameManager_Frank_GameOver : MonoBehaviour
     {
         private GameManager_Frank_Master gameManagerMaster;
         private Player_Master playerMaster;
         public GameObject panelGameOver;
 
 
         void OnEnable()
 
         {
             SetInitalReferecnes();
             {
 
                 gameManagerMaster.GameOverEvent += TurnOnGameOverPanel;
 
             }
 
         }
 
         void OnDisable()
 
         {
             gameManagerMaster.GameOverEvent -= TurnOnGameOverPanel;
 
         }
 
         void SetInitalReferecnes()
         {
             gameManagerMaster = GetComponent<GameManager_Frank_Master>();
         } 
 
         void TurnOnGameOverPanel()
 
         {
             if (panelGameOver != null)
             {
 
                 panelGameOver.SetActive(true);
                 yield return new WaitForSeconds(6);
                 Application.LoadLevel(1);
             }
         }
 
     }
 }