K3B fails to burn DVD-RW discs

[Filippos Klironomos]

? 
> When I ejected the blank DVD+RW's after the failed burn, they appear to
> have data written on the inner part of the disc, but K3B doesn't even
> start the write before it fails. 
>

What does 'dvd+rw-mediainfo' return when you have DVD+RW in the drive?

Notice as well that you should turn off automount when you want to
burn things on CD/DVD. First you have to burn and then mount. So if
you get a pop up window after inserting the DVD or CD in the drive,
close the window and make sure the CD or DVD is not mounted anymore
before you burn.