Ios problem with www class

enter code herehey there
I wanted to get a xml file from a webserver. It worked perfect for android and pc, but I can’t get the connection on ios. I think ios got problems with the www class, but I also think its possible and I’ve got a mistake in the coroutine. Please have a look at my code, maybe youre able to help me:

Debug.Log("ERROR: " + www.error) shows me "ERROR: ".

crossdomin.xml is on the server

void Start(){
   StartCoroutine(StartLoading());
}

IEnumerator StartLoading(){
   string url = "http://www.pixcube.com/games_ad/AppData.xml";
   WWW www = new WWW(url);
   while(!www.isDone)
      yield return null;

   if (www.error == null){
      XmlDocument xmlDoc = new XmlDocument();
      xmlDoc.LoadXml(www.data);
      ProcessAppLinks(xmlDoc.SelectNodes("AppLinks/AppLink"));
   }else{
      Debug.Log("ERROR: " + www.error);
   }	
}

private void ProcessAppLinks(XmlNodeList nodes){
   foreach (XmlNode node in nodes){
      //get all infos out of the xml node
      StartCoroutine(DownloadImage(nodeWithImageWebLink));
   }
}

IEnumerator DownloadImage(string url){
   WWW www = new WWW(url);
   while(!www.isDone)
      yield return null;
		
   imageArray.Add(www.texture);

}

I have the same Issues, but not with all WWW requests. I even tried to configure xCodes NSAppTransportSecurity to allow http downloads. Nothing helped. If smo. know a better solution pls help. Thank’s