title: Orchard CMS search index module does not index all of my documents
body: <p>after i made some changes to some documents from the dashboard, they were not displayed as results of my back-end search, i update the "search index" and the same result, so i "Rebuild the search index". Now after a few minutes the search index contains almost all of my documents(not all) so the search does not match some content.
  Anybody knows why? please help and thanks.</p>