Error in Web Service consumption (org.xml.sax.SAXParseException)

Some idea of how to correct the error:

  

(org.xml.sax.SAXParseException) org.xml.sax.SAXParseException;   lineNumber: 1; columnNumber: 1; The content is not allowed in the   prologue

When I try to consume a web service, on line 3 of the code shown below:

DocumentBuilder builder = null;
builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();            
Document xmlDocument = builder.parse(new ByteArrayInputStream(result.getArchivo()));