Can't return library e-book; get "Please authorize your computer first" error even though computer IS authorized

I just got a new computer, and am trying to manage the e-books I have checked out from my public library. I authorized my computer through ADE, but when I right-click and choose the Return Borrowed Item option,l I get an error message saying that I need to authorize my computer first. I am beyond frustrated -- I have erased and re-done the authorization, uninstalled and re-installed ADE, rebooted... nothing fixes it.