Does anyone know this message: "Document root element is missing"

Question

I'm getting this message by loading an XML File from my server into an DocumentBuilder. The only strange thing, if I'm doing that from my local machine (linux) it works, but executing by Java WebStart I get the message above !?!
Does anyone know why?

Answer 1

That was the first idea i had, but InputStream.available() on the given File means something about 3500 signs.
Somewhere I read, that a Classpath, or Path may be missing, but I'm not using any special imports!
package com.msgis.XML;
import java.io.*;
import org.xml.sax.*;
import org.xml.sax.helpers.DefaultHandler;
//API
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.FactoryConfigurationError;
import javax.xml.parsers.ParserConfigurationException;
//Exceptions
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;
//Reading XML File
import java.io.File;
import java.io.IOException;
//DOM definition and Exceptions
import org.w3c.dom.Document;
import org.w3c.dom.DOMException;
//URL
import java.net.URL;
import java.net.*;
Ideas?
That is the only idea left, because, in the IDE (Sun ONE Studio 5 Update 1, Standard Edition) it works, and from other projects I know that the IDE is linking its own classes.
java pgm does not work. It delivers the same Exception.
SAXParseException Document blablabla .......