I would suggest that you get to either DP 7.01 or 7.03 by installing the patch bundle, located at
http://support.openview.hp.com/selfsolve/patches
If you run the Backup interactively, when it is done, does it give you a popup "Backup Completed Successfully"?
Does it print the Session Statistics?
I suspect that either this is just a GUI problem, or, the backup is Completing, but not actually Finishing, and this would have to be addressed by implementing KeepAlive