WWW.text not display to UI Text.text

Hi , Why the download.text is displayed on Console but not in mytext.text UI ?

IEnumerator Start () { // Create a form object for sending high score data to the server WWWForm form = new WWWForm();

     form.AddField( "id", id );
 
     // Create a download object
     WWW download = new WWW( url, form );

     // Wait until the download is done
     yield return download;

     if(!string.IsNullOrEmpty(download.error)) {
         print( "Error downloading: " + download.error );
     } else {
         
         result=download.text;

         Text mytext = GetComponent<Text> ();
         mytext.text = result;

         Debug.Log(result);
         }

     }
 }