It might be as it's title suggests Sony DVD-RW a -RW only you might have to change it to do +RW to a duel format one click here try here for an example if you wish to stick with sony (they do all makes).
I think you will find that your Sony DW-23A is a dual format writer, and it is also a rebadged Liteon SOHW 1653S, if your Mesh pc is a fairly new one I would get in touch with them. It could also be the brand of dvd blank you are using.
Is it really THAT important that your recorder writes to DVD+R? I've stopped using them altogether, as DVD-R's are cheaper & more readily available. Also, if you're writing DVD movies, many players struggle with DVD+R, whilst most work with DVD-R just fine.
I had the very same Sony drive in a Mesh PC, and it was OK, but should you come to upgrade or add another drive, you should be looking at the latest Samsung or Pioneer models.
Oh, forget about the fuss over dual layer writers, the cost of the blanks makes them hardly worth using.
In a nutshell.... Go and buy 50 Bulkpac DVD-R's for a tenner, then burn away to your hearts content (at that price, you won't even be bothered if you have a few that fail writing). Forget about the +R's, they'll be obsolete before you know it, IMHO.