Why won't some dvd players play dvd+/-r?

I have a collection of DVD Frisbees to prove that not all players like all media. I have 10 different makers DVD-R's. I have found that ones that work on one player will not work at all on another. I burn a test clip to all the media and try them on every different player to find out what works on that player. Some are sensitive to burn speed. So I always burn at the slowest speed for players. I reserve the fast speed for computer use only. But that has gotten me in trouble also as I now have Data DVDs that cannot be read because the drive I burned them on died.

I would only add that you should try different brands of media. I have made DVD+R recordings and sent them to about a dozen people, and so far no-one has complained. Maybe your recorder drive is defective.

Because : 1 technology changes. 2. It is the way the DVD player was made and function. If it is important to you that you player be able to play dvd+/-r, then when you buy a player make sure that it can by looking on the specs, they tell what functions your dvd player can do.