FIX GraphStoreExample : multiple Commands in store.execute{} had a bad syntax 

But I found a problem:

    val graphAsString = RDFXMLWriter.asString(gr, base = timblCard) getOrElse sys.error("coudn't serialize the graph")

( line 65 ) returns an empty string,
although the gr:Rdf#Graph object looks good when calling :
    println(gr)