Vintagecollect:
This is still the "dirty little secret" of the DVD world, and one which occasionally sets me off reminiscing fondly for the good old days of VHS tapes which, while offering relatively ratty picture quality, were pretty much bulletproof: they
always worked no matter who you sent them to (except for overseas, but that's another story.)
Recorded DVDs, both DVD+R and DVD-R (pronounced DVD-dash-R, not minus-R by the way -- where's the logic in that?) still suffer from playback compatibility problems, as you have found out. You'll usually be ok, but the conventional wisdom is that somewhere above about 80% of all players will play one or both of these recorded formats reliably, with that percentage constantly rising as older models are retired and more "recorded DVD compatible" models come on the market. But that means that around 2 out of 10 machines still
might not play a recorded DVD reliably! And I had someone just a few months ago who was unable to play a recorded DVD I made on either of his brand new brand name set-top DVD players, so go figure.
A huge variable seems to be the media itself. One brand frequently gives me a lot of playback trouble even on my most compatible players, while other brands, even cheap no-name ones seem quite reliable. It's a mess that the industry seems to be keeping awfully quiet about!
The reason is that the information on recorded DVDs is actually a series of darkened spots created on a photosensitive dye surface by a laser during the write process. This is significantly different from the "pits" (which are actual pits!) stamped into aluminum on a replicated DVD. Replicated DVDs are universally compatible with all players, but are very expensive to make. (Well, the first one is expensive, then the next hundred thousand are dirt cheap
) Recorded DVDs are actually a clever "cheat", simulating the pits of the original DVD spec and DVD players have been engineered to be able to read the lighter and darker areas of the dye in the same way as the reflected/nonreflected light from the stamped DVDs.
One piece of good news: most all recorded DVDs will play in your computer. Try that if you have a DVD drive and a software DVD player. Since this is a compatibility issue, you could also ask the seller if they would be willing to supply you with a copy on DVD+R (assuming your existing copy is -R, or vice versa), that might do the trick. Or, believe it or not, sometimes a copy on an RW (rewritable) DVD will play when an R won't! And don't discount the possibility that you simply got a bad copy.
If you expect to be using recorded DVDs, this might not be a bad time to splurge thirty bucks or so and get a new player.
If you're really stuck, let me know what's on your DVD (I probably have it) or send it to me and I'll make you another copy which
might play ok for you.
--Dave