why does my dvd player say incorrect disk ?

Answer 1

there several possible problem:

you bought a DVD from another country (different region code)

Your DVD player cannot read some of those DVD burnt by a computer or a DVD-RW

your DVD might have severe data error

the content in DVD might be just data, burnt by PC

Answer 2

Looks like an old DVD player. If you put a + disc in a player that only plays - disks then that may produce the message. Also, if your disc is too scratched up or putting a blank disc in.