windows 10 – Volume not showing up in Diskpart

I plugged Seagate 1 TB external hard disk into my computer and used Diskpart to check the detail information of disk. I can correctly select the USB drive. However, when I type detail disk in Diskpart, I receive an error message: there are no volumes. Why and how to fix this error?
Hint: Hard disk does not show up anywhere except in Device Manager.