OnNonEmptyCDRW is not fired even that NERO_BURN_FLAG_DETECT_NON_EMPTY_CDRW flag is provided with BurnIsoAudioCD. Do I have to consider other thinks to make it works like the selected MediaType, other flags, some settings in the ISOTrack,.....

My Code:
drive.BurnIsoAudioCD("", "Orders", 0, isotrack, Nothing, Nothing, NERO_BURN_FLAGS.NERO_BURN_FLAG_DETECT_NON_EMPTY_CDRW Or NERO_BURN_FLAGS.NERO_BURN_FLAG_WRITE, 0, NERO_MEDIA_TYPE.NERO_MEDIA_CD)


Private Sub nero_OnNonEmptyCDRW(ByRef Response As NEROLib.NERO_RESPONSE) Handles nero.OnNonEmptyCDRW
mensaje.msjInformativo(" El CD-R/CD-RW no esta vacio!" + Chr(13) + Chr(10))
Response = NERO_RESPONSE.NERO_RETURN_EXIT
End Sub

Ops! Sorry, I did not ready your post completely before. This is my call that will raise the event.

Call mobjDrive.BurnFileSystemContent _
(mobjFileSystem, _
NERO_BURN_FLAG_VERIFY Or _
NERO_BURN_FLAG_WRITE Or _
NERO_BURN_FLAG_DETECT_NON_EMPTY_CDRW, _
mlngSpeed, _
NERO_MEDIA_CDRW)


You may try using the NERO_BURN_FLAG_DETECT_NON_EMPTY_CDRW flag.