your problem probably isn't the backup itselves, but the archiving process of the database that got stuck.
You probably don't see yesterday's historical data right?
First check the item 'maintenance', 'archiving status'
if it doesn't say it did it for the last day,
then you should run the 'system setup' , 'data summarizing'
and it will restart the summarizing process
If you want you can manually run the backup from 'maintenance', 'backup data'
Rob