Can't access USB hard drive plugged in to Time Capsule
I see the same symptoms on my setup-- Used to use the usb hdd all the time on my old Windows setup, am able to see it on my macbook just fine. We are probably working in NTFS which, however, is clearly not allowed:


  Note: ExFAT and NTFS formats aren't supported.


Per http://support.apple.com/kb/HT2426