Hover Script Help

This C# code is giving me trouble, I don’t know how to fix this error! Please tell me what to fix.

Here is the code:

using UnityEngine;
using System.Collections;

public class hoverScript : MonoBehaviour {

public string levelToLoad;
public AudioClip Soundhover;
public AudioClip ClickSound;
public bool QuitButton = false;

// Use this for initialization
void Start () 
{

}

// Update is called once per frame
void Update () 
{

}

public void OnMouseEnter ()
{
	audio.PlayOneShot(Soundhover);	
}

public void OnMouseUp ()
{
	audio.PlayOneShot(ClickSound);
	yield return new WaitForSeconds(0.35);
	if(QuitButton)
	{
		Application.Quit();	
	}
	
	else
	{
		Application.LoadLevel(levelToLoad);	
	}
    }

}

Here is the error:

Assets/Scripts/hoverScript.cs(28,21): error CS1624: The body of hoverScript.OnMouseUp()' cannot be an iterator block because void’ is not an iterator interface type

You cannot yield in a void. The method has to be of IEnumerator type e.g:

IEnumerator YieldHere()
{
    yield return new WaitForSeconds(0.35f);
}