From: Taiwan, R.O.C
If you can get your discs (DVD-R, DVD+R DL) to play on other DVD-Player, then that will help to clarify the problem.
For DVD-R media, although most of the DVD-Players are able to read them, but in some cases, the problem is due to writing quality. Which means, you might have a bad burned on your disc, bad media or bad burner.
For DVD+R DL disc, you need to make sure if it has been doen with bitsetting (Book Type set to DVD-ROM).
Most of DVD-Player can not recognize DVD+R DL media, then you will get the result as "No Disk"....