DOM Parsing

I am using Java Server Pages to call a Java Bean that parses an XML document(mapDoc) , looks for an element tag(data) and replaces text in the first tag(SQL) with a new value(an SQL string). Here is a code snippet...

DocumentBuilderFactory dbfactory = DocumentBuilderFactory.newInstance();

DocumentBuilder docbuilder = dbfactory.newDocumentBuilder();

mapDoc = docbuilder.parse(mapFileName);
...

}
Element root = mapDoc.getDocumentElement();

Node dataNode0 = root.getElementsByTagName("data").item(0);

Element dataElement0 = (Element)dataNode0;

dataElement0.setAttribute("sql",sql);

return mapDoc;
}
...

When I run the code in JBuilder5 which uses Tomcat 3.2, it works fine and the XML document is updated with the new text. However - when I run it outside of JBuilder in Tomcat 4.01, it gives me a null result when I print out the string output of the document mapDoc. Any ideas?