Validate XMl loaded from URL

I want to validate xml documetn aganst xsd schema, the validation seems not validating the document when its loaded from url.

have tried to validate a xml document that is located on local disk and it went well but not when im loading xml from url How can i validate it ? Im sure that the xml is loaded to xDoxument. here my code

   XmlSchemaSet scehma = new XmlSchemaSet();
        scehma.Add("", @"C:\MySchema.xsd");


          XDocument xmlDocument = XDocument.Load(urlString, LoadOptions.PreserveWhitespace);

          xmlDocument.Validate(scehma, (s, e) =>
        {
            Console.Write(e.Message);

            isValidated = true;
        });