Problem using castor (import)

I have a problem with using castor to generate source files from a schema 
(
http://www.3gpp.org/ftp/Specs/archive/23_series/23.140/schema/REL-5-MM7-1-3 
), since this schema import another schema (
http://schemas.xmlsoap.org/soap/envelope/ ). Does anyone know what the 
problem is? Urgent!  Thank you in advance.

I used command line as below:
set CASTOR_LIB=C:\SPOTJava\SPOTMMS\lib
set CASTOR_DEST=C:\SPOTJava\SPOTMMS\src
set 
CASTOR_CLASSPATH=%CASTOR_LIB%\castor-0.9.4.3.jar;%CASTOR_LIB%\dom4j-full.jar;%CASTOR_LIB%\xerces-J_1.4.0.jar;%CASTOR_LIB%\apache-regexp.jar
java -cp %CASTOR_CLASSPATH% org.exolab.castor.builder.SourceGenerator -i 
REL-5-MM7-1-3.xsd -package com.voiceage.SPOTxde.castor -dest %CASTOR_DEST% 
 

I got error message:

Error reading import file 'http://schemas.xmlsoap.org/soap/envelope/': 
java.net.UnknownHostException: schemas.xmlsoap.org
        at 
org.exolab.castor.xml.schema.reader.ImportUnmarshaller.<init>(ImportUnmarshaller.java:181)
        at 
org.exolab.castor.xml.schema.reader.SchemaUnmarshaller.startElement(SchemaUnmarshaller.java:420)
        at 
org.exolab.castor.xml.schema.reader.Sax2ComponentReader.startElement(Sax2ComponentReader.java:253)
        at 
org.apache.xerces.parsers.SAXParser.startElement(SAXParser.java:1340)

        at 
org.apache.xerces.validators.common.XMLValidator.callStartElement(XMLValidator.java:1197)
        at 
org.apache.xerces.framework.XMLDocumentScanner.scanElement(XMLDocumentScanner.java:1862)
        at 
org.apache.xerces.framework.XMLDocumentScanner$ContentDispatcher.dispatch(XMLDocumentScanner.java:1238)
        at 
org.apache.xerces.framework.XMLDocumentScanner.parseSome(XMLDocumentScanner.java:381)
        at 
org.apache.xerces.framework.XMLParser.parse(XMLParser.java:1035)
        at 
org.exolab.castor.builder.SourceGenerator.generateSource(SourceGenerator.java:527)
        at 
org.exolab.castor.builder.SourceGenerator.generateSource(SourceGenerator.java:580)
        at 
org.exolab.castor.builder.SourceGenerator.main(SourceGenerator.java:1135)

Best Regards,
Jenny