WaitForSeconds not working

Hello , I tried to create a simple splashscreen. at first this waitforseconds working, but suddenly after a few week this code doesn’t want to work. I tried using debug.log but I just get the “before waiting” and the “after waiting” doesn’t appear even after 5 minutes. I am using unity 4.5, why this is happen?

void Start () {
		guiTexture.pixelInset = new Rect (0, 0, Screen.width, Screen.height);
		StartCoroutine (LoadNextScene ());
	}
	IEnumerator LoadNextScene(){
		Debug.Log ("before wait");
		yield return new WaitForSeconds (DelayTime);
		Debug.Log ("after wait");
		if (NextLevel != "") {
			Application .LoadLevel (NextLevel );	
		}
	}

IEnumerator Start ()
{

 Debug.Log ("before wait");
         yield return new WaitForSeconds (5f);
         Debug.Log ("after wait");
}

use this it will work delaytime keep it initailly as 5f ;