[branav]

I have no problems recording TV Programs using DVD+RW, but when I place a new DVD-RW disc and initialize it, the machine does not recognize the formatted disc at all. The recorder rejects the disc and says "Unknown disc. Please check disc again." Results are the same irrespective to "VR" or "Video Mode" type formatting. My DVD Recorder is: LG Model LRY-517 that should work with both DVD-RW as well as DVD+RW. The DVD+RW that I've been using successfully happens to be of Sony, and the DVD-RW I am facing the strange problem happens to be of TDK, both of whom I have great confidence.
I took the initialized disc that my recorder rejected and placed it on my PC, just to see what my PC sees. My PC says "Insert a blank disc."

[Broadz]

All DVD recorders have certain brands of disk that they like, and other brands that they don't. Sounds like your DVD-RW is a brand that your DVD recorder does not like. If your PC does not recognise it either, it might just be a dodgy disc. Try another of the same brand, but this time try it in your PC first. If that one isn't recognised either, avoid the brand in future.