Time Machine time axis empty

Hi! Time Machine has always been working correctly but I no longer can make it work. I noticed no backup was available, only "Now" is in the time axis. So, I erased the entire disk and tried to set it up again, but still it doesn't work. 30GBs has been stored, but nothing is in the time axis except "Now". Any idea why it is not backing up?
Thanks!

 

Starting standard backup
Backing up to: /Volumes/Time Machine Backups/Backups.backupdb
No pre-backup thinning needed: 3.38 GB requested (including padding), 57.21 GB available
Copied 588 files (1.8 GB) from volume MacBook.
No pre-backup thinning needed: 1.20 GB requested (including padding), 55.39 GB available
Copied 132 files (573 KB) from volume MacBook.
Starting post-backup thinning
Deleted backup /Volumes/Time Machine Backups/Backups.backupdb/Luca Carlon’s MacBook/2010-01-08-124228: 55.41 GB now available
Post-back up thinning complete: 1 expired backups removed
Backup completed successfully.

I can't see anything strange... But I still see only "Now"... Any other idea?
Thanks for your help!