DataProtectorPlus Error sheduled Backup Fails

[Vasudevan.B]

Chelsea Engineering Pvt Ltd Chennai.
Data Protector Express 3.50-sp2.ERROR is 4030 illegal request & Error 1040: No devices specified or all devices are now offline.

When i format all the medias in the D2D the error is resolved.but when i freshly start the back with GFS-62 mode & etc. modes the backup runs for 2 days or more till the D2D storage disk of 24 catridges are reached without the utilisation of the full capacity.
Then this error starts.
Till that period the backup job complete successfully.

regards
vasudevan.