If you selected backups only weekly or monthly, then the backup server skips your machine on the other days of the week or month. Currently, a backup report is only sent if a backup was attempted on at least one of the file systems for a particular machine. It didn't backup when I expected. The approximate start schedule is as follows. In most cases, your machine is grouped with several other machines so the actual start and end time of your backup will vary.
Delays do occur on rare occasions.
The backup software will attempt to complete a backup for 24 hours, so sometimes you may notice a backup still running from the previous day.