catching comments in SAX

[kanghao]

my handler looks like ---------------
public class RMSAXDefaultHandler extends DefaultHandler implements LexicalHandler {
...
...
public void comment(char[] ch, int start, int length) throws SAXException {
System.out.println("comment ===============");
String comment = new String(ch, start, length);
xml_value = xml_value + comment;
}
...
...
}
in my appllication --------------
RMSAXDefaultHandler handler = new RMSAXDefaultHandler(list);
SAXParserFactory factory = SAXParserFactory.newInstance();
factory.setValidating(validating);
factory.newSAXParser().parse(new File(filename), handler);

I can't seem to catch comment event.
what's wrong?