there are several reasons for backup schedule not to run...
1. If you have configured the calender based backup schedule you will need to check whether you have properly configured the schedule. you will need to define the backup windows as well as desired days of month/ week from the calender
2. If you have properly configured the schedule then you can -
a. update the NBEM lob list by running the
nbpemreq -updatepolicies command
b. you can check the prediction of the next schedule by running below mentioned command
nbpemreq -predict -date mm/dd/yy 6:00:00 (choose the next day )
check whether it shows your scheduled job in prediction...
let us know whether this resolve the issue