wd mybook studio connected to Time Capsule keeps sleeping

Hello, I have a 1st Generation Time Capsule with a 500 GB hard drive inside. As you can expect, that size is not really big enough for today's computers with 750 GB drives.

So I went an bought a WD MyBook Studio 3TD external drive with USB and FireWire 800.

I went and connected the WD drive to my Time Capsule via USB to back up my MacBook Pro with a 750 GB drive.

It works fine until… the WD desides that it hasn't been used for a while and puts itself into low power sleep mode. The little white light on the external drive starts flashing.

When it is time for the next hourly back the Time Capsule doesn't seem to be able to spin up the drive again to back-up. I get a message that the back-up has been delayed and the Time Machine System Preference says "Time Machine Error The backup disk is not available. Latest successful backup: Today 6:22 PM".

It is now 10:16 PM and before 7:00 PM I left the house to go grocery shopping and closed my laptop to save battery. I look at the drive and it is sleeping (white light blinking slowly).

I've used the included SmartWare software to tell the drive to never sleep, and yet it still is doing it.

Suggestions?