I've been using a cron job to backup my site with innobackupex using incremental backups for several months now. However I just noticed that since about a month ago the backups haven't been updating. By that I mean that the the data in my backup is a month old even when I apply the new incremental backup to it. I tried to manually create a fresh full backup but even that is stuck creating a backup that's about one month old. What could the problem be?