IBook Store error message "you cannot update this item"

Question

When my book was finally in the iBookstore, I purchased it, to see how the process works and if everything is ok for a potential customer. Turned out that I mad some minor mistakes, which I fixed (hopefully) and published an new Version (successfully, I guess). Now I need to update the purchased book to cheeck if everything is ok.
There IS an Update in the iBookstore, but trying to run the update ends up in an error message "you cannot update this item".
My fault? Not my fault? What to do?
Has anyone an idea?

Answer 1

It took quite a while to find this:
Dear xy,
Thank you for purchasing “Inside Apple”. A new version of the book is available to you at no charge.
Here is how to download the new version:
1) Tap the iBooks app on your iPad, iPhone or iPod touch. If you are already in the iBookstore, tap on “Library”.
2) Tap the “Edit” button.
3) Locate “Inside Apple”, tap “Edit” and then “Delete” to delete the book.
4) Tap the “Done” button.
5) Tap the “Store” button, scroll down to the bottom of the page and sign out of your account.
6) The page will refresh. Scroll down to the bottom of the page and sign back in to your account.
7) If you are not already in the “Purchases” page, tap the “Purchases” icon at the bottom right corner of your screen.
8) Locate “Inside Apple” in your purchases and tap the “Redownload” button.
You will now have the updated version of the iBook in your library. Thank you for being a loyal Apple customer and have a great day!
Sincerely,
iTunes Store Team