I can't help with your question (I never reported a Case to Ellis Island).
However, I have a tip for an alternate search method when an Ellis Island search doesn't work.
Are you familiar with the One-Step Webpages by Stephen P. Morse? (go to stevemorse.org)
IMHO, his search engine is much more useful, because:
1) You can search Ellis Island and Castle Garden (1855-1891 and 1892-1957 arrivals)
2) You can search arrivals from earlier years in NYC and other cities
3) You can search the Ellis Island Manifests (aka Missing Manifests) in one step
Also, I think it's easier to search with other criteria (say part of a city name), or with limited passenger name. For example, I found my g-g.father using C* C* for first and last names. His last name was so badly mangled in the records, Ellis Island searches weren't productive.
Also, the tool will also send an email with a summary of all search results (if you provide an email address). It's very helpful when you're trying to fine YOUR JACOB PETERSON from the 90 that immigrated from Sweden in 1892-93, and were born in 1865-70.
He also has tools to help with the US Census searches. His search tools were very helpful tracking down my immigrant ancestors (who all disappeared for at least one census cycle).
-Ken
Researching surnames Pedroncelli and Pilatti in Sondrio; Cantoia in Novara; Penna in Asti.