I am doing site search using examine. I followed umbraco tv to configure my two files and copy the code to my page_load event handler in my user control used to list search results.

  SearchTerm = Request.QueryString["search"];

      if (string.IsNullOrEmpty(SearchTerm)) return;

      var criteria = ExamineManager.Instance

        .SearchProviderCollection["someSearcher"]

        .CreateSearchCriteria();

      var filter = criteria

        .GroupedOr(new string[] { "nodeName", "textBody" }, SearchTerm)

        .Not().Field("umbracoNaviHide", "1")

        .Compile();

      var a = ExamineManager.Instance.SearchProviderCollection["someSearcher"];

      SearchResults = a.Search(filter);

I does not work for some search terms and i will get a null reference exception when executing SearchResults = a.Search(filter);

When I comment out .search statement and print out the filter on the screen using response.write instead, i will see { SearchIndexType: , LuceneQuery: +(nodeName:My Search Term textBody:My Search Term) -umbracoNaviHide:1 } when working properly.

but in the cases where exceptions are thrown, response.write(filter) shows:

{ SearchIndexType: , LuceneQuery: +(null null) -umbracoNaviHide:1 } 

Does anybody know why?