JSI Tip 2324. Windows 2000 NTBackup generates invalid/inconsistent return codes.

If you are testing the ERRORLEVEL returned by NTBackup, it should return a 0 for a successful backup and a non-zero for an error.

NTBackup may return a 0 when the backup fails and it may return different values for the same ending state, even when the command line switches are the same.

I wrote the batch script in tip 2265, so you could avoid the cost of a good backup, but now you should consider investing in one. I recommend TapeWare.