Problem to discover a Web service descriptor

I created a ws descriptor and when I try to put the url in File/URL field, the system say me that I have a http error (401).

I am surprise because when I put the url in a browser (like chrome or IE), the browser display me the wsdl.
I retry the same things in a browser on the IS Server and I have no problem to.

When I try to access to the URL via a little C# program, I have no problem.

when I use the web service descriptor as consumer in the WebMethod designer, it generates the error I said.

Kindly share your IS version with fix levels.

Also the error with screen shots if any from designer during the creation of WSD consumer.