the reason for this is that we are pretty strict on the stopwords here on ez.no. The words you search for is very common here and hence we exclude them.
via internal:
http://ez.no/community/contribs/3rd_party/firefox_plugin_to_advanced_search_ez_no_docs
via google: http://ez.no/community/contribs/3rd_party/ez_search_firefox_plugin_via_google