Perform the following troubleshooting steps:
- Check that you have the latest version of Nokia Reading app on your Lumia device.
- Check that the date and time are set correctly on your Lumia device.
- Check that your devices network connection is working with other applications (for example with Browser or Email).
- Check that the network (mobile data) signal coverage is good. For example you shouldn't download books when travelling by train.
- Reboot your device and try to download again.
- Try to download via Wi-Fi instead.
- Try to download again later.
If the above steps do not help then contact Nokia Care.