OK, I found myself, :) and now I would like to register a book, but I won't get the books BCID. I entered the ISBN with and without dashes, and triple checked everything, but when I click "register book" (or whatever the button says) I get the same page but some information of the book is gone - like ISBN, author and title. All the previous books were wery easy to register, I don't understand what's wrong with this one. And there's no shortcut in registering finnish books.
It's not necessary to have or use the ISBN to register a book. Simply leave that spot blank and manually enter the Title, Author and Category for the book. I've found that many of the books I've registered either don't have an ISBN or the ISBN shows incorrectly in the database, so I've used this method frequently. Disadvantage - you won't get any cover art.
How about logging out of bookcrossing (see the link on the left side, under your bookshelf, edit your profile, etc.), exiting the browser, restarting the browser and logging in again? Sometimes this helps :)
Thanks again, now it worked. I tried again from another computer and left the ISBN blank (which I actually tried earlier too, it just didn't work then...). Oh well, computers, I don't get them, but somehow I manage to use them.