I am inclined to think you are using -R media, as it is well know that at least DVDA1 will not work with that combination. And now, it appears as if the same holds for DVDA2. Try your Plextoer with +R media, both DVDA1 and DVDA2 and I think it may work.
Like to know what you experience. I'm holding on upgrading to DVDA2 until I am satisfied that it will work with the Plextor/-R combination. Until then, Nero.
The 504 is a +R only drive so that is all I use. I don't have any experience with -R. With DVDA 2, I can burn to a Verbatim +R but I cannot burn to a +RW disk. So, there is no testing on an RW before burning an R.
I use an old version of RecordNow Max to burn both +R and +RW disks and it works flawlessly.
I've got a 504A and I've never had any problems using it with DVDA. I've used both +R and +RW, all Verbatim.
Make sure you deactivate things like antivirus programs, etc. They've never caused me any problems, but since these programs "interfere" with file access it can't hurt to try.
I have the Plextor 708A. DVD-A 2 does not recognize the existence of that drive. Neither does DVD-A 1. Is it possible that Sony is creating its software so that it only works with Sony brand drives?