Corrupted Backups on NAS-Devices (Netgear Duo Pro)

My Backup of System-Disk (C:) will be done over LAN on a Netgear Duo Pro NAS-diskarray.
I'm using Windows7 Professional.
The Backup did work very well several times. But recently it ends with an error: "fehlerhafte Datensicherung, bitte Verbindungsdaten überprüfen" (Sorry, Iuse a german based Acrojnis True image). I renewed the (correct) connection dates, the result rests unchanged.
And I find a curious additional share on the NAS-device containing all other existing shares. I can't see this share on other Computers, which also use this NAS-device as location of backups.

I found a workaround for this problem:
- delete the backup task
- creating a new one (with identical conditions)

The phantom no longer exists!

I think, that True Image doesn't work correct in such environment. And I would like to get a "Service Pack".