I write 900 mp3 songs to dvd+R DISC.BUT OPEN AND PLAY 324 SONGS ONLY IN DVD PLAYERS?

The DVD players don't have the processing power to display that... erm... huge lot you have there. It's common sense.

Check the bitrates and the capabilities of the player. Some players may not be able to play MP3 files with bitrates greater than 192 kbps. Since bitrates can go all the way up to 320 kbps, you might be out of luck with certain songs unless you convert them.