Can't use a database loaded by tdbloader2

[Guido Zuccarelli]

I loaded a tdb with 2 ttl files for testing. It worked well:
INFO  Total: 30 tuples : 0.20 seconds : 146.34 tuples/sec [2014/07/08 12:16:28 
ART]
 12:16:28 Index phase
 12:16:28 Index SPO
 12:16:28 Build SPO
 12:16:28 Index POS
 12:16:28 Build POS
 12:16:29 Index OSP
 12:16:29 Build OSP
 12:16:30 Index phase end
 12:16:30 -- TDB Bulk Loader Finish
 12:16:30 -- 4 seconds

Then I checked it on jena:

TDB.getContext().set(TDB.symUnionDefaultGraph, true);
String directory = "database";
Dataset dataset = TDBFactory.createDataset(directory);
Iterator<String> names = dataset.listNames();
while (names.hasNext())
     System.out.println(names.next());

I got 0 names.
I also tried with get all triples with SPARQL, with 0 results.
Am i doing something wrong?

Best regards,
Guido Zuccarelli.