QUOTE("from your other thread")
Time Machine backup fails. If I click on backup, it goes through. Don't know how to resolve this one.
Easiest way will be to use the Time Machine Pref Panel to reset the desired volume. I'd suggest changing the volume to another one, close the panel, then open it immediately and set it back to the one you really want. 
Alternatively or additionally, you might want to simply rename the "~[whateverYourBackupFileIsNamed] backups" file for the one you KNOW is not the one you want to use. Then, double check that you have the 'correct' one selected in the Pref Panel. If you don't intend to use that old backup, you might as well delete it and recover the space.
..... If you don't intend to use that old backup, you might as well delete it and recover the space.
Now there's a warm soft one to step on....
And how are we to know "If you don't intend to use it"???
Just asking...
Bob K. rnkiii