ND-4570A not writing +R DL DVD

Hello, I’m new to cdfreaks; I’ve just joined.

I have an ND-4570A which I bought new and has been working OK for writing/reading
DVDs ±R and RW. Just recently I bought some dual layer +R DVDs and the drive
does not appear to either recognise these as blank nor write to them. From what I’ve read I understand that such media should be within the capacity of the drive.
Is there a firmware limitation here and can it be fixed, or do I need to look for a more
up to date drive?

I’m running a 32bit version of Debian Lenny OS.

What media are you trying to write. We know it’s DVD+RDL. What brand?
What firmware version is in your drive?
What program are you using to burn that media?