Another thought, - if something you normally do suddenly does not work this week, ... ebay has been 'tinkering' a lot with the site appearance lately, so maybe just wait a few hours to a day or two and try again. The Purchase History icons continue to change, - foolish, in my opinion, when so many really useful changes could be implemented instead. Anyway, if you cannot Archive something for now, I'd say not to worry and try again later.
