My Time Capsule is old and gives lots of errors in backups, so I bought a (LaCie) external HDD to connect it to and do my Time Machine backups from that instead; Apple tells me I can do this. As per Apple's instructions I reformatted the external HD with the new name and plugged it into the Time Capsule. I immediately got a notification on my computer asking me if I wanted to do a Time Machine backup on the newly named HD. I thought "great" and said yes... and then it refused to recognize it after that.
In Time Machine preferences the new HD didn't appear, only the old Time Capsule. I go to AirPort Utility to the Time Capsule and go to Edit/Disks; "Enable file sharing" is turned on but only the Time Capsule appears there, not the new HD. Disk Utility doesn't recognize the new HD, nor does it appear on Locations in the finder sidebar or on Volumes in the terminal. The new HD is plugged in and its power light on the back is on, and the computer recognized it when it was plugged in before, but nothing. How can I get my Mac to recognize the HD and back up to it?