[H] Bad burner?

[Winterlight]

I have a NEC RW ND 3540A that plays DVDs or anything else just fine 
but when I try to burn something it won't recognize that there is a 
blank DVD in the drive.
 It does not matter what  burner program I am using, I have tried 3. 
I have a dual boot machine 64 bit Win7/Vista and the same problem 
exists in both OS's which rules out a setting or some other software problem.

Anybody have any ideas... or is it time for a replacement?
thanks