Win 8.1 cannot drag audiobook to iPhone via iTunes

[nottarf]

Hello, I have no access to my iMac at the moment so I am using a PC windows
8.1.
Installed iTunes on the PC and downloaded 2 audiobooks but when I try and drag the books to my iPhone 5 (attached to the PC via USB) I get a red circle and the books just sit in the library.
iTunes sees my previous audiobooks on the iPhone.

Note: iTunes does not display the phone number just the serial number.

Could someone shine some light on this?
Thank you.

 

[maflynn]

Maybe because your iPhone is linked to your other computer and you can't add content using another computer, i.e., it helps with anti-piracy or apple doesn't want this ability to cause more problems then its worth.