burned dvds wont play on ant dvd player

[cazthies]

ive downloaded films and burned them using windows 7 dvd maker on discs dvd+r some work others dont so i tried dvd-r it burned fine said it was succesful but wont play on a dvd player what can i do

 

[popatim]

Did you finalize the burn or leave it open like in multi-session?

Also are you burning the movie as a data disk (wont play on most dvd players) or as a dvd movie?
What software are you using?