I bought an e-book in buecher.de and downloaded it to my ADE. After authorisation of both my ADE and my reader (PocketBook Pro 603) I tried to open it. In ADE it works perfectly but as I want to copy it to my reader, it gives me an error. (German version: Zieldatei xxx konnte nicht übertragen werden, English translation (I guess): target file xxx could not be transferred.)
Strangely it works now after I tried it once again. I can not explain it because I did not change anything.