MyBook Essential Smartware not seeing multiple internal hard drives

I have 2 internal hard drives on a MacPro, and WD Smartware only sees one of them (the one with the System folder). According to the help there is supposed to be a drop-down menu on the Home tab of Smartware to choose the other internal hard drive – there is no such drop-down menu. Any ideas are appreciated.

This feature is not available on the Mac version

I prefer using Time Machine and backup all drives

Wow. Yet another reason to avoid purchasing Western Digital products.