gwt xml getelementbyid

Hi, in this code fragment:

 

1. Document doc = XmlParser.parse("<root><a id="a"/></root>");

2. doc.getElementById("a");

 

the second line gives "null".

 

I found some info on this (must be a DTD with 'id' declared as 'ID'), but there is no special example how to do this.

Could somebody give a concrete example how to use getElementById in this two code line?

 

THANK YOU!