No writable partition found

What does this mean? I have gotten the message in the past and the SmartWare eventually found my target drive. Now, I click all over the GUI and my target drive never appears (a tethered 2 TB drive).

ADDED LATER
Well, the target drive was eventually found. At least five minutes passed with no indication that there was a writable partition in the waiting.

That message means WD SmartWare is unable to detect a compatible target hard drive. With regards to a NAS, it can happen when the application is still scanning your network and is yet to detect available shares within your unit.