"undefined" - if XML attribute contains German special chars (üõöä)

Hello!
I found out that if XML file’s attribute contains German special chars (chars with umlaut, like: üõöä - ä ü ö) then I get “undefined” answer when I try to read an attributes value. I tryed to change XML file encoding to: “UTF-8” and “iso-8859-1” but still no luck. "system.useCodepage = true; " doesn’t help as well :-/