As wesociety says, the chances are that your copy of Nero is an OEM one that's restricted to work only with a limited number of drives.
I'd be very careful of using serial numbers 'found' on the Internet - someone has mentioned that many of those that are 'in the wild' have been disabled in the latest releases. They are also illegal. If this is your problem, you can upgrade to the full version of Nero 6 (gaining various features that aren't in the OEM version) using your OEM serial number to give you the cheaper 'upgrade' price.
On the other hand, the problem may be that you haven't got a late enough build of Nero installed. If you're using Nero 5.5, you need at least 220.127.116.11 for the ND-2500A drive to be recognised. I don't know what the minimum version of Nero 6 that will work is, but I'd suggest using the latest 18.104.22.168 if you have Nero 6 anyway.