[xwiki-users] How to activate Search on

Hi, I'm trying, see my previous mails and sorry for these newbie questions ;-( , to make my Wiki runs after an update (my wiki is hosted on *.myxwiki.org). When I perform a search there is no results and an error is return : "Lucene is not installed see wiki.cfg". I have checked documentation and my xwikipreferences document : - Lucene seems to be activated by default on XWiki - in preferences: addon Lucene is installed and configured has default search Engine. But I have also noticed that Lucene status returns code instead of values ($lucene.luceneDocCount and $lucene.queueSize). How can I enable a search Engine (Lucene or Solr)? Thanks for your help, Best regards, Nam