Copy or rip games and movies to DVD-RW

[loffler]

I have succesfully backed up ps2 ganes and movies to DVD-R and work great. I am now trying to backup to DVD-RW, but the software does not recognise the media as being blank.
I normally use PrimoDVD 2 for games and Smartripper and Gear DVD for movies, but they keep saying "insert blank media".
I know it must be possible. Can someone tell me the best way of doing this.
Thanks