If you have a Sony Reader, you may have trouble transferring titles from Adobe Digital Editions (ADE) to your device. The best way to resolve that issue is to transfer titles to your Reader using Sony's Reader for PC/Mac software.
If you have already downloaded titles to Adobe Digital Editions, you'll need to import them to Reader for PC/Mac.
How to transfer Adobe Digital Editions eBooks to Reader for PC/Mac
- Open Reader for PC/Mac, then go to File > Import Files.
- Find the EPUB you want to import, then double-click it.
ADE stores them here by default: [My] Documents/My Digital Editions.
The title you picked should open in Reader for PC/Mac. From there, you can plug in your device and transfer titles.