dvd players won't work?

i have 3 different machines and all of them come up with no disc when i try to play a film. What am i doing wrong. I have occasionally had a film playing but generally all films won't play on any of my dvd players. I have changed the scart leads. Can anyone help. I am buying full price films and still they won't play. Always no disc or unknown comes up on screen. Help.

lebeau
February 2009