Why would this work one way but not another?

If I have a bat file:

“C:\Program Files\Nero\Nero 7\Core\NeroCmd.exe” --write --drivename “Sony DVD RW DRU-810A” --real --dvd --image c:\myISOfile.iso --speed 4 --force_erase_disc

It will put this iso file on the DVD and it will have the Volumn Label and play as a DVD in any player…

However, if I use this command from VB:

Dim cmdline As String
cmdline = “C:\Program Files\Nero\Nero 7\Core\NeroCmd.exe”
cmdline = cmdline & " --write --drivename " & Chr(34) & AvailableDevices.SelectedItem & Chr(34) & " --real --dvd --image c:\myISOfile.iso --speed 4 --force_erase_disc"

        Shell(cmdline, AppWinStyle.Hide, False)

It will sometimes, but not all the time make Windows XP think it is a CD-ROM instead of the DVD. Also, it doesn’t put the Volumn ID of the disc properly either.