name='MrT']I had a Liteon dvd recorder which was supposed to record to all formats Dvd+/-r, DVD+/-rw. Despite this specification the machine struggled to record or playback any discs in the -r/-rw formats. Occasionally it would recognise a -r disc but more often the message *no disc" appeared! So in my simplistic way I just stuck with +r/+rw discs and was very happy with the results obtained.
Dvd players can also struggle to read both formats. To even up scores I have one player that will only read +r and another that prefers -r, whilst my trusty Pioneer reads everything!
The moral of this is - if you have a disc in either format and your machine fails to read it, try it on some other machines before deciding that it is the disc at fault.
Mike (MrT)