KOReader: Dropbox: Fail

I installed KOReader on my new Libra and am still exploring it. I tried activating the DropBox access. I put the token (long stream of letters and digits) into the box and hit go. I just got a dialogue about 'no such folder' or something similar. Does it actually work? I wondered if the wifi was off when I tried to activate it but I think it was on. All my books are on DropBox so its important to be able to access it. i since discovered an email from DropBox checking it was me... Perhaps I should again?