Karaoke VCD copy

I have a Karaoke VCD player. It can play copies from original. I have a burner (Plextor: PX-W8432Ti Internal), I copied a karaoke vcd. It will play in my computer,pioneer dvd karaoke player but not on my old karaoke vcd player. I still have old karaoke vcd copies that still play in the old player. Why is the new copy not playing in the old karaoke vcd player????