Message Title

I am not able to perform a faceted discrete request.
My configuration is based on a working document on which I already run 'normal' requests.

	@Field(analyze = Analyze.NO)
	@Facet
	private long dateByTen;

		final FullTextEntityManager fullTextEntityManager = Search.getFullTextEntityManager(entityManager);
		final QueryBuilder builder = fullTextEntityManager.getSearchFactory().buildQueryBuilder().forEntity(Phrase.class).get();
		final FacetingRequest phraseFacetingRequest = builder.facet()
			    .name("phrases")
			    .onField("dateByTen")
			    .discrete()
			    .orderedBy(FacetSortOrder.FIELD_VALUE)
			    .includeZeroCounts(false)
			    .maxFacetCount(3)
			    .createFacetingRequest();
		
		// create a fulltext query
		final Query luceneQuery = builder.all().createQuery();
		final FullTextQuery fullTextQuery = fullTextEntityManager.createFullTextQuery(luceneQuery, Phrase.class);
		
		// retrieve facet manager and apply faceting request
		final FacetManager facetManager = fullTextQuery.getFacetManager();
		facetManager.enableFaceting(phraseFacetingRequest);
		
		final List<Facet> facets = facetManager.getFacets("phrases");

The exception described in title is raised at search time. While in debug there is the following nested exception :

java.lang.IllegalArgumentException: field "$facets" was not indexed with SortedSetDocValues

The code looks inside the 'fieldInfo' map for the '$facets' field. But this map contain only the filedname I've defined in the document. I don't understand why it's not looking for the 'dateByTen' field instead of '$facets'