NEC 3500 DL Compability

Hi,
I got a NEC 3500 dvd burner which supports dual layer discs I bought an Intenso DVD+R DL (RITEK-D01-01) and when I tried to burn on it said:

Illegal disc

Illegal disc

Could not perform end of Disc At Onvce

I also attached an image of the error.

what can I do?

This is why everyone says not to buy Ritek.

You could try a firmware upgrade, but a Verbatim DVD+R DL would be the best solution.

I got the original firmware 2.16 which firmware will do the job if any?