There is a problem with the configuration of your iPhone. Please restore with iTunes and reinstall iBooks.
In order to fix this, you can install iBooksFix2 , from the insanelyi.com repo via Cydia.
This fix is an updated version of iBooks Fix we previously detailed, which was introduced during the days of the Greenp0ison 4.2.1 jailbreak.
Now thanks to a simple fix available on Cydia, you can now easily fix iBooks from the device itself, follow the steps in this tutorial by @UnlockBoot.
How to Fix iBooks Error via Cydia ?
Step 1. Launch Cydia –> Manage –> Sources –> Edit –> Add
Step 2. Enter the following repository: http://repo.insanelyi.com , tap Add Source.
Step 3. Search for’iBooksFix2’ and install it.