Bakup did not start at the scheduled time?????

Hi all

Yesterday I scheduled my backup as usual at 1:00am and to my surprise the logs showed me that the backup was started at 9:30am in the morning............

In the morning when I tried to login I could not, I saw the status of the database it was shut down so I manually started the database which caused the backup that was started at 9:30am(which i could not see that it was running) terminated with errors.....................

Can any one please tell me how come the backup did not start at the scheduled time. However the backup of the next day was sucessfull.

Regards

Mahesh