Why does old text in GUILayout not disappear?

The GUILabel shown in the picture below is the problem. When the text of the label is updated the old text remains and is not cleared, what am I doing wrong? This only occurs in the built version, not in the editor.

void OnGUI()
{
   GUILayout.Label(PhotonNetwork.connectionStateDetailed.ToString());
}

The solution to this problem was to add a Camera to the Scene.