External HDD with eSATA connection not recognized

[Jm44jg39]

I am running Win 8.1 Pro 64 bit. I have a WD "red" HDD connected externally in a NexStar-NX box. The NexStar supports USB 3.0 and eSATA. The USB 3.0 connection works fine and shows up in WIN 8.1 disk manager and all files are accessable. When I use a eSATA cable (have tried 2 different ones) the HDD is not recognized by Win 8.1. Win 7 HP 64 bit sees the eSATA connection and all works well. The HDD, when using the eSATA connection, shows up in the post boot screen as I have the HDD listed in the BIOS. I would like to use the eSATA connection as I'm short of USB 3.0 ports on my ASUS Maximus V Gene mob.
Any suggestions or is this a Win 8.1 quirk?

 

[Edwin]

Two things come to mind:
I'm wondering if power to the drive needs to be governed internally when connected via SATA;
it may also need to be brought 'Online' as in the screenshot:

 

[Jm44jg39]

Thanks, I will check this out. Right now the drive uses external power.