Error when burning to a dvd+rw

[macho271]

Hi, I have some dvd+rw's.. 6 of them to be exactly..
Anyway.. I have used those to burn dvd's and it worked fine.. Then I bought some dvd+r's and have used those for a while.. Now I was going to burn a movie to the dvd+rw's that I got to check if the video works on my standalone dvdplayer so that I wont waste any dvd+r's on it.
When I try to burn with nero i get this message:
"Please insert a medium to write"

and with copytodvd:
"no writers found on this system. Can't continue"

Whats wrong? I have burned on those dvd+rw's before..
I have a hp200
and the media: ePreformance

Yes, I know is dvd+rw because I have burned many times on them.. and the dvdplayer in my computer reads them!

[Capmaster]

Crappy media?

[macho271]

hmm.. maybe.. but I realy dont think thats the problem.. because none of the dvd+rws work..!