Nice application, but update wont download.

Running OSX 10.8.5 on my Mac. App Store says theres an update for Bookpedia, but it wont load. Trying to update returns this message:

Bookpedia failed to download
Use the Purchases page to try again.

But trying to update from the Purchases page returns the same message. Whats wrong? And please fix it!

Kazymyra about Bookpedia