No database can ever be backed up by VSS or VSP - databases need to be transactionally consistent and an open file agent doesn't guarantee that.
You need an agent - something like the MS SQL agent. Alternatively, you may be able to write a script that runs on the client to backup the database to a disk location and then back up that backup file using NetBackup. That's what we do with most of our SQL and Oracle databases
As always, after you've put your backup solution together, test a recovery of that database and see if it still works.
A Google search for "netbackup sql server express" will certainly help you.
…/Ed
Ed Wilts, RHCE, BCFP,
BCSD, SCSP, SCSE