GROUP_CONCAT in a query to dbpedia

[Luis Daniel Ibáñez González]

Hi,

I've been playing with Jena (v. 2.6.4 with ARQ 2.8.7) using dbpedia's
endpoint, and the following query:

SELECT  ?title (GROUP_CONCAT(?platforms) AS ?plat)
WHERE
  { ?game <http://purl.org/dc/terms/subject> <
http://dbpedia.org/resource/Category:First-person_shooters> .
    ?game foaf:name ?title .
    ?game dbpprop:platforms ?platforms
  }
GROUP BY ?title

parsed from String with the proper constructor yields:

Exception in thread "main" HttpException: HttpException: 400 Bad Request:
HttpException: 400 Bad Request
        at
com.hp.hpl.jena.sparql.engine.http.HttpQuery.execCommon(HttpQuery.java:337)
        at
com.hp.hpl.jena.sparql.engine.http.HttpQuery.execGet(HttpQuery.java:189)
        at
com.hp.hpl.jena.sparql.engine.http.HttpQuery.exec(HttpQuery.java:144)
        at
com.hp.hpl.jena.sparql.engine.http.QueryEngineHTTP.execSelect(QueryEngineHTTP.java:133)
        at jenatest.Main.main(Main.java:58)

either using default syntax or ARQ syntax.

If i use "Count" it works with both syntax.

Nothing special with the factories, I used:

Query query = QueryFactory.create(queryString,Syntax.syntaxARQ);
QueryExecution qexec = QueryExecutionFactory.sparqlService("
http://dbpedia.org/sparql";, query);

before the execution.

Am I doing something wrong?

Thanks in advance for your help.

-- 
Ing. Luis Daniel Ibáñez G.