that is so embarassing, there is space problem in the query:
String service = "http://dbpedia.org/sparql";
String queryString = "";
queryString = "PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#> SELECT ?label " +
"WHERE {" +
"<http://dbpedia.org/resource/Quatre_Bornes> <http://dbpedia.org/ontology/country> ?y ."+
"?y rdfs:label ?label ."+
"FILTER (LANG(?label) = 'en')"+
"}";