XML AppendChild not working

Hello.

Can anyone point out what's wrong with this XML generation code? (It's only one method in a bigger class.) I have one player in the players list, but the resulting XML file consists of nothing but , even though the "Writing playerData" debug line gets fired.

  function SaveXML(){
                 var playersPath : String = Application.dataPath + "/players/";
                 var document : XmlDocument = new XmlDocument();
                 var rootElement : XmlElement = document.CreateElement("root");
                 document.AppendChild(rootElement);
                 for (var playerData : PlayerData in players){
                         Debug.Log("Writing playerData");
                         var playerNode : XmlElement = document.CreateElement("player");
                         rootElement.AppendChild(playerNode);
  
                 }
                 var writer : XmlTextWriter = new XmlTextWriter(playersPath + "players.xml", System.Text.Encoding.Unicode);
                 document.WriteTo(writer);
                 writer.Close();
         }