Why can't I back up a USB stick to my NAS

I'm selecting a folder backup, and successfully defining a backup.  When running the backup, I get the error:

 

-Snapshot error %1.

--Error EBAB03F1: Unspecified error.

I set up the backup as follows:

Folders to back up:
 F:\
  Include subfolders
  Back up all files

Backup schedule:
 At 22:00 every Monday, starting 20/06/2009

Options:
 Backup name: USB003 - Green Kingston 2gb
 Backup destination: \\nas\mydata\Backups\
 [  ] Save backup files to a unique subfolder
 Description: USB Bckup

 

The preview partially works as I have more files on the stick than it's 10,000.

 

As a side note,  I oiginally had trouble defining the backup task as  I got the error "Cannot add protection".  Fortunately I resolved it using a workaround kindly provided by Spud57

http://community.norton.com/norton/board/message?board.id=other&message.id=8995&query.id=278698#M8995

 

I'd really appreciate any help.  I have a number of USB keys I need to backup.