My SPARQL query is not working on DBPesdia.org. :    This is my SPARQL query and its not working on dbpedia.org

PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>

PREFIX owl: <http://www.w3.org/2002/07/owl#>

PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>

PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>

PREFIX uni: http://www.semanticweb.org/admin/ontologies/2017/4/untitled ontology-19#

SELECT ?property ?subject ?prop ?object 
    WHERE {
               uni:Product ?property ?subject .
                  OPTIONAL {
                               ?subject ?prop ?object
                            }
  
          }

