Failure in loading RDF-schema during RDF validation by Sirpac

Hi,
I tried to run Sirpac from a workstation within a LAN with a proxy server. I had the following error:
FAILED to load RDF schema 'http://www.w3.org/2000/01/rdf-schema#' [java.net.SocketException: no further information (code=10051)]

So I tried to customize the Sirpac Java source this way:

..........

try {

Handler hnd = new Handler("proxy.csata.tno.it",8080);

URL url = new URL (null,sURI,hnd);

String sContentType = url.openConnection().getContentType();

.........

Then I had this new error message:

[java.net.NoRouteToHostException: Operation timed out: no further information]

Can someone help me to solve this problem?

Thanks!

Giuseppe Bux