Quoting a question from an user :
"Having said that, I can't seem to buy this as IAP? I have the first app, and clicking yes on the notification in that asking me if I want to buy the second book just pops up a black screen with a done button and the title "List of purchases". I've tried leaving it for ages to load, closing and reopening the app, using it on wifi and without wifi, deleting and reinstalling the app from the store... nothing seems to work. System's an iPhone 4, 4.3.3 (I think), and jailbroken - iTunes store receipt available on request, of course."
My answer:
"Note from the devs : The Gold Edition works like a breeze.
Base FL game : I have indeed realized that our lead coder, for the former FL app, forgot a "submit" button in the uploading process for the in-app feature, causing the list to be empty. You won't be charged there's just nothing you can buy at the moment.
We'll do an update asap but unfortunately, Apple is telling us that we have to upload again the whole thing and again wait 10 days.........................
Another good reason to buy the Gold Edition
Otherwise you'll have to wait a bit longer, we are deeply sorry.
Human mistake. "