I have a copy of 3 pages of the manifest (from Vesterheim Genealogical Center) of the Steamship "Etna" that arrived in New York from Liverpool on July 6, 1868. My great grandparents and their children are listed. I can't find this ship and passengers on your website. Although everyone on the page (I have) is from Norway, in the column "the country to which they severally (sic) belong" is listed as Sweden. Technically, they belonged to Sweden in 1868. As they were not listed as Norwegian, is that why this ship and passengers are not listed in your records?
The ships and passenger lists on this site are for departures from Norway. The Etna left from Liverpool. The people on the Etna would have taken a "feeder ship" from Norway to England. As to not finding the passengers, as noted on the Emigrant Search Page "NOTE: The database is not complete. There are many years from which no lists exists (read more about this in the article "Hunting Passenger Lists"). There are also many lists not transcribed yet. By browsing indexes of ships year by year, you will be able to see what lists are in the database." Carla