why why why can't I?

Hi all, I have been burning for a couple of months now and have a lot of issues. I have a sony DRU-71A I am using lastest version of nero. Most of this is greek to me as of yet so I don't mess with the settings except the one which is the type of burn (book type I believe ya call it). I was told to set it at dvd-rom for best compatibility during playback on dvd players. I am using ritek G04 as well. I was also told to use ritek -r's as they are most compatible as well. Is it possible that a dvd player will play only dvd +r media and not -r? Is my problem related with my booksetting (dvd-rom). Not sure what the prob is. Anyways on a couple of dvd players they will not even recognize the -r and I was under the impression that they would recognize -r before +r. If some could give me some input on this it would be greatly appreciated. Thanks, Dave