How to get My Cloud to recognize a My Book on the USB port?

My Cloud OS 3 Personal & Network Attached Storage My Cloud
1

I have a My Book plugged into the USB port the the 3 TB My Cloud. Nothing is detected by My Cloud on the USB port.  The My Book works fine when I plug it into the network.   Any secrets to making the My Book work on the My Cloud USB connection? 

2

did the my cloud recognize other usb devices? how du you format the my book?
normally the my cloud detects any attached usb HDD