I've just run across this problem. The worst thing is that neither your website or the toolbar says that it won't allow you to bookmark FTP sites, it just says that the bookmarking has failed leading you to believe that if you just try again later it will work. Either support it, or add more useful error messages and a mention of this in your documentation.

Hi - I've managed to import my bookmarks (via html file) from Delicious, but although it's applied my original tags to my bookmarks, none of those tags are available in 'My Tags'. Do I just need to wait for 'Stage 2' of the process to complete, or has something gone wrong with the import?