Please call 1.800.THE.BOOK for technical support.
When you ask for help here it is best if you supply what OS you are using, what version of the software you have, do you have a WiFi connection when you attempt to download your book? Which iPhone are you using? As far as I know this is not known issue, so most folk here would only be able to give you some hints on trying to help you out.
At this point TS is your best bet.