Fuseki text search: ?literal unbound

[Neubert, Joachim]

I've tried one of the text search syntaxes described in 
http://jena.apache.org/documentation/query/text-query.html, namely

(?s ?score ?literal) text:query 'word' # ... and original literal value

It works fine for ?score, but the ?literal variable remains unbound. 
(fuseki-2.3.0)

Any ideas?

My index definition is like that:

:gnd rdf:type      text:TextDataset ;
    text:dataset <#gndDb> ;
    text:index   <#gndIndex> ;
    .

<#gndIndex> a text:TextIndexLucene ;
    text:directory <file:/opt/thes/var/gnd/latest/tdb_lucene> ;
    text:entityMap <#entMapFull> ;
    .

<#entMapFull> a text:EntityMap ;
    text:entityField      "uri" ;
    text:defaultField     "text" ;
    text:defaultPredicate rdfs:label ;
    text:uidField         "uid" ; ## recommended for Skosmos 1.4+
    text:langField        "lang" ; ## required for Skosmos 1.4

    text:map (

        # skos:prefLabel
         [ text:field "keyword" ;
           text:predicate skos:prefLabel ;
           text:analyzer [ a text:LowerCaseKeywordAnalyzer ]
         ]

# ....
  ) .

An executable query is at

http://zbw.eu/beta/sparql-lab/?endpoint=http://zbw.eu/beta/sparql/gnd/query&queryRef=https://api.github.com/repos/jneubert/sparql-queries/contents/gnd/search_corporate_body.rq