IndexOutOfBoundsException when extracting XML with Transformer

I want to extract specific nodes from a large XML file.

That works well in test cases with small XML files, but when I use my real XML file, I get following output:

FEHLER:  ''
javax.xml.transform.TransformerException: java.lang.IndexOutOfBoundsException
    at com.sun.org.apache.xalan.internal.xsltc.trax.TransformerImpl.transform(TransformerImpl.java:732)
    at com.sun.org.apache.xalan.internal.xsltc.trax.TransformerImpl.transform(TransformerImpl.java:336)
    at xml_test.XML_Test.extractXML2(XML_Test.java:698)
    at xml_test.XML_Test.main(XML_Test.java:811)
Caused by: java.lang.IndexOutOfBoundsException
    at com.sun.org.apache.xerces.internal.impl.XMLStreamReaderImpl.getTextCharacters(XMLStreamReaderImpl.java:1143)
    at com.sun.org.apache.xalan.internal.xsltc.trax.StAXStream2SAX.handleCharacters(StAXStream2SAX.java:261)
    at com.sun.org.apache.xalan.internal.xsltc.trax.StAXStream2SAX.bridge(StAXStream2SAX.java:171)
    at com.sun.org.apache.xalan.internal.xsltc.trax.StAXStream2SAX.parse(StAXStream2SAX.java:120)
    at com.sun.org.apache.xalan.internal.xsltc.trax.TransformerImpl.transformIdentity(TransformerImpl.java:674)
    at com.sun.org.apache.xalan.internal.xsltc.trax.TransformerImpl.transform(TransformerImpl.java:723)
    ... 3 more
---------
java.lang.IndexOutOfBoundsException
    at com.sun.org.apache.xerces.internal.impl.XMLStreamReaderImpl.getTextCharacters(XMLStreamReaderImpl.java:1143)
    at com.sun.org.apache.xalan.internal.xsltc.trax.StAXStream2SAX.handleCharacters(StAXStream2SAX.java:261)
    at com.sun.org.apache.xalan.internal.xsltc.trax.StAXStream2SAX.bridge(StAXStream2SAX.java:171)
    at com.sun.org.apache.xalan.internal.xsltc.trax.StAXStream2SAX.parse(StAXStream2SAX.java:120)
    at com.sun.org.apache.xalan.internal.xsltc.trax.TransformerImpl.transformIdentity(TransformerImpl.java:674)
    at com.sun.org.apache.xalan.internal.xsltc.trax.TransformerImpl.transform(TransformerImpl.java:723)
    at com.sun.org.apache.xalan.internal.xsltc.trax.TransformerImpl.transform(TransformerImpl.java:336)
    at xml_test.XML_Test.extractXML2(XML_Test.java:698)
    at xml_test.XML_Test.main(XML_Test.java:811)

The code:

InputStream stream = new FileInputStream("C:\\myFile.xml");
StreamSource source = new StreamSource(stream);
XMLInputFactory factory = XMLInputFactory.newInstance();
XMLStreamReader reader = factory.createXMLStreamReader(source);

TransformerFactory tf = TransformerFactory.newInstance();
Transformer t = tf.newTransformer();

String extractPath = "/Hotels/Hotel";
String path = "";

while(reader.hasNext()) {
    reader.next();

    if(reader.isStartElement()) {
        path += "/" + reader.getLocalName();

        if(path.equals(extractPath)) {
            StringWriter writer = new StringWriter();
            StAXSource src = new StAXSource(reader);
            StreamResult res = new StreamResult(writer);
            t.transform(src, res); // Exception thrown

            System.out.println(writer.toString());

            path = path.substring(0, path.lastIndexOf("/"));
        }
    }
    else if(reader.isEndElement()) {
        path = path.substring(0, path.lastIndexOf("/"));
    }
}

The XML file is not malformed since I successfully validated it. Pretty-printed it's about 7000 lines long. Maybe that's too much?