Java XSLT transformation problem

Hi,
   I am trying to transform a very large XML document using DOM4J in Java. Here's what I do:

1. Read in the original XML file using SAXReader (reader is a SAXReader object):
Document myDoc = reader.read(new File("very_large_xml_file.xml"))...

2. Pass the Document myDoc to the following function that transforms the file:

public Document stylesheet_trans(Document document, String stylesheet)
            throws Exception
      {
        // load the transformer using JAXP
        TransformerFactory factory = TransformerFactory.newInstance();
        Transformer transformer = factory.newTransformer(
            new StreamSource(stylesheet)
        );

        // now lets style the given document
        DocumentSource source = new DocumentSource(document);
        DocumentResult result = new DocumentResult();
        transformer.transform(source, result);

        // return the transformed document
        Document transformedDoc = result.getDocument();
        return transformedDoc;
    }

finally, write the returned Document to a new file:

final_file = new FileWriter("final_transformed_large_xml_file.xml");
returned_doc.write(final_file);

The problem here is, when I opened the final_transformed_large_xml_file.xml in a browser, it tells me that the document is truncated (that is, the transformation process seems unable to handle such a large original file...) -- there is no real problem with the actual tag transformations, but it is just cut off before the end. Can anyone help me with this problem?