xml validator problem

Hi, I am doing a xml validation now. below is my code:
import org.xml.sax.helpers.DefaultHandler;
import org.xml.sax.*;
import javax.xml.parsers.*;
import java.io.File;
import java.io.FileInputStream;
public class validator {

public static void main(String[] args) {
try {
String xmlpath = "D:\\documents\\abc.xml";
File xmlf = new File(xmlpath);

DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
dbf.setValidating(true);
dbf.setNamespaceAware(true);
DocumentBuilder db = dbf.newDocumentBuilder();
db.setEntityResolver(new EntityResolver() {
public InputSource resolveEntity(String publicId, String systemId) {
String schemapath = "D:\\documents\\cde.xsd";
File schemaf = new File(schemapath);
try {
FileInputStream fis = new FileInputStream(schemaf);
return new InputSource(fis);
}
catch (Exception e) {return null;}
}
});
db.setErrorHandler(new DefaultHandler() {
public void error(SAXParseException e) throws SAXParseException { throw e; }
public void fatalError(SAXParseException e) throws SAXParseException { throw e; }
public void warning(SAXParseException e) throws SAXParseException {
System.out.println( e.toString() );
}
});

db.parse(xmlf);
}
catch (Exception e) {
e.printStackTrace();
}

}

}
---------------------------------
the xsd is correct. And the xml is valid i think. but when i run this program, it give me the following error.
org.xml.sax.SAXParseException: Valid documents must have a <!DOCTYPE declaration
.
org.xml.sax.SAXParseException: Element type "CollaborationProtocolProfile" is no
t declared.
at org.apache.crimson.parser.Parser2.error(Unknown Source)
at org.apache.crimson.parser.Parser2.maybeElement(Unknown Source)
at org.apache.crimson.parser.Parser2.parseInternal(Unknown Source)
at org.apache.crimson.parser.Parser2.parse(Unknown Source)
at org.apache.crimson.parser.XMLReaderImpl.parse(Unknown Source)
at org.apache.crimson.jaxp.DocumentBuilderImpl.parse(Unknown Source)
at javax.xml.parsers.DocumentBuilder.parse(Unknown Source)
at validator.main(validator.java:39)
-------------------------------------
for the first error, i don't know what it means.
for the second error, i have declared it in the schema, but why still said not defined?
can anybody shed some lite...

Are you referencing your Schema document from the XML document?
Here's an example from w3schools.com:

.This tutorial may also help u further.