Empty Query - More Like This (Lucene) -

i'm new @ java , lucene. i'm trying simple mlt test, i'm not getting results.

import java.io.file; import org.apache.lucene.analysis.standard.standardanalyzer; import org.apache.lucene.document.document; import org.apache.lucene.document.field; import org.apache.lucene.index.indexwriter; import org.apache.lucene.index.indexwriterconfig; import org.apache.lucene.search.indexsearcher; import org.apache.lucene.search.query; import org.apache.lucene.search.scoredoc; import org.apache.lucene.store.directory; import org.apache.lucene.util.version; import org.apache.lucene.index.directoryreader; import java.io.ioexception; import org.apache.lucene.document.stringfield; import org.apache.lucene.document.textfield; import org.apache.lucene.queries.mlt.morelikethis; import org.apache.lucene.queryparser.classic.parseexception; import org.apache.lucene.search.topdocs; import org.apache.lucene.store.simplefsdirectory;  public class hellolucene {   public static void main(string[] args) throws ioexception, parseexception {     standardanalyzer analyzer = new standardanalyzer(version.lucene_40);      string indexpath = "c:/users/name/desktop/lucene";     directory index = new simplefsdirectory(new file(indexpath));       indexwriterconfig config = new indexwriterconfig(version.lucene_40, analyzer);      indexwriter w = new indexwriter(index, config);     adddoc(w, "lucene in action", "193398817");     adddoc(w, "lucene dummies", "55320055z");     adddoc(w, "managing gigabytes", "55063554a");     adddoc(w, "the art of computer science", "9900333x");     w.close();        indexreader reader = directoryreader.open(index);     system.out.println("reader has " + reader.numdocs() + " docs on it.");      morelikethis mlt = new morelikethis(reader);     mlt.setmintermfreq(1);     mlt.setmindocfreq(1);     query query = mlt.like(0); //doc id      indexsearcher searcher = new indexsearcher(reader);         topdocs topdocs = searcher.search(query,5);      system.out.println("found " + topdocs.totalhits + " hits.");      (scoredoc scoredoc : topdocs.scoredocs) {         document doc = searcher.doc(scoredoc.doc);         system.out.println(scoredoc.doc + ". " + doc.get("isbn") + "\t" + doc.get("title"));     }          reader.close();    }    private static void adddoc(indexwriter w, string title, string isbn) throws ioexception {     document doc = new document();     doc.add(new textfield("title", title, field.store.yes));      // use string field isbn because don't want tokenized     doc.add(new stringfield("isbn", isbn, field.store.yes));     w.adddocument(doc);   } } 

and get:

reader has 4 docs on it.
found 0 hits.

i tried using luke check doc's id , there nothing wrong apparently.
did tests there, dont know whats wrong :(
did lot of searching on web, said settings mintermfreq , mindocfreq, tried 1 , 0, got nothing.

does have idea?
in advance!

[solved] edited:

its working now!
had add this:

mlt.setanalyzer(analyzer); mlt.setfieldnames(new string[] {"title"}); 

its working now! had add this:

mlt.setanalyzer(analyzer); mlt.setfieldnames(new string[] {"title"});