Have you seen this?
http://wiki.contribs.org/USBDisks It has more information then you need but has some great troubleshooting tips on how to identify your usb drive and what some of the troubleshooting steps could be.
>NTFS will not mount as it is not recognized by SME
>I am very wary of USB drive backups with SME. The problem I have seen in my testing is that the drive will mount automatically the first time you plug it in. When you unplug it it will not unmount immediately, if it does not unmount correctly it leaves a mount point much as you describe below. If you then do a backup it will backup to that mount point directory on the local drive and show that it completed correctly.
noticed that the system will indeed verify if there is a usb disk available. but when i run the backup it will make the backup in:
/media/New_Volume
I have never seen this exact behavior on a machine that had a usb drive plugged in for the first time and had it mounted correctly. For me as long as the mount point is correct and pointing at a drive with the correct type of filesystem (Not NTFS) the backup works fine.