WD hard drive,Time Machine, Airport Extreme help

[KSUWILDCAT]

I have a question for all you Mac Masters out there. This is my first post so be easy on me. After my wife's Hard drive just crashed and lost all her photo's, (she is in the photography business) I decided I had to get a external Hard drive to back everything up. Right now my set up is this: I have a my new 3 TB WD hard drive connected to a Dynex powered 4 port USB hub connected to my airport extreme. I have another external HD connected the same way that holds all my iTunes songs and movies. As I said before my wife has a iMac and I have a MacBook Pro. The WD HD has 2 partitions currently on it,(1 TB for me and 3 TB for her) I have Time Machine directed to the appropriate partition. I successfully backed up my MacBook when the HD was directly connected to the computer but when I am trying to do it through AE, it says it is in use. I haven't had a chance to try the iMac b/c it is still getting the new HD put in. I expect the same problem with it. I'm new to the Mac's so I am not sure where to even start. TM can see the drive but when I go to back up it always comes back as a failed attempt and says this "The backup disk image "volumes/..........sparsebundle" is already in use" Any ideas?

 

[S.B.G]

If you haven't solved this issue yet, try the steps on this page:

C12. "The Backup disk image ... sparsebundle ... is already in use."

It sounds similar to what you're describing.

First, make sure the Disk Image containing your network backups isn’t mounted anywhere, either on your Mac or another one on your local network. If you’re not sure whether a mounted disk image will appear, from a Finder window, or after clicking an empty area on your desktop, select Finder > Preferences > General (for the desktop) and/or Finder > Preferences > Sidebar (for Finder windows' sidebar), and be sure the box for External Disks is checked.

If it's shown in a Finder sidebar, eject it. If it's on your desktop, right-click it and select Eject.

If that doesn’t help,

start Airport Utility and click Manual Setup at the bottom.

Click the Disks icon in the toolbar (or Settings > Disks from the menubar).

That will show any connected disks and partitions. Select the disk in question and click the Disconnect All Users button.

You’ll get a prompt for a confirmation.

Then each user connected to that disk will get a notice.
Once they’ve all closed their connections and clicked OK, unplug or disconnect the disk momentarily, then reconnect it.