I am processing cXml orders and the xml begins with the following:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE cXML SYSTEM "http://xml.cxml.org/schemas/cXML/1.2.017/
cXML.dtd">

I am attempting to use the following code to transform the xml:

     XslCompiledTransform transform = new XslCompiledTransform();
     Stream resultStream = new MemoryStream();

     XmlReader xslRdr = XmlReader.Create(new StringReader(xslSheet));

     transform.Load(xslRdr);

     XmlReaderSettings xRdrSettings = new XmlReaderSettings();
     xRdrSettings.ProhibitDtd = false;
     xRdrSettings.ValidationType = ValidationType.DTD;

     XmlReader xmlRdr = XmlReader.Create(cxmlFilename, xRdrSettings);
     transform.Transform(xmlRdr, null, resultStream);

My problem is that in my organization, my test machine cannot access
the url in the DOCTYPE without proxy authentication.  I get this
exception when running the code:

"An error has occurred while opening external DTD 'http://xml.cxml.org/
schemas/cXML/1.2.017/cXML.dtd': The remote server returned an error:
(407) Proxy Authentication Required."

Can anyone point me to some examples of how to apply the proxy
authentication?

I attempted to  create an XmlUriResolver with the proper proxy
credentials, and passed that into the XmlReaderSettings.XmlResolver
property, but that made no difference.  I must be missing something
easy.

Any help would be appreciated.

Thanks,

Chris