Hi!
I believe you mean the following: You have a job configured to run on Saturday, you forgot to insert the tape, but the job started anyway... It saved nothing because there was no tape in the drive, but nevertheless, that job will keep asking for a tape unless you cancel it. If you don't cancel it, as soon as you insert an overwritable (or appendable tape, it depends on how it's configured the job), the job will start saving in the tape.
If the scenario I said, is what's happening then there is a way to configure backup exec to cancel the job if it asks for a tape for an X time.
Regards,