Verion编号XML 1.1无效

Question

我的代码中的这一行会导致此异常

          Uri endpoint = new Uri("http://dbpedia.org");
        string query = "SELECT ?cat   WHERE { <http://dbpedia.org/resource/London> dcterms:subject ?cat .}";

        SparqlRemoteEndpoint source = new SparqlRemoteEndpoint(new Uri("http://dbpedia.org/sparql"), "http://dbpedia.org");
        SparqlResultSet resultSet = new SparqlResultSet();
        resultSet = source.=QueryWithResultSet(query);

请帮助我 thanx