How do i sync my audiobooks to my ipod nano 4th generation?

What kind of audiobooks (publisher, file format, etc...)? If your books are Audible audiobooks I believe you must register the device with Audible.com. Maybe you don't have enough space on your iod to actually fit the audiobook?

And do you sync using your laptop or computer?

I have 1/2 of my memory to spare!

Thank you but I discovered a better way: manually sync them

If you would like to use a third-party software, u can go to try Macsome Audioboook Converter. I often use it, which can remove DRM protection and convert them to MP3. In this way, u can transfer them to any audio devices.