If you mean burnt MP3 on a DVD disc..... Burnt disc are known to be finicky, oftentimes it will only play on the box that it was burned (sounds stupid I know but this is real life). It depends on the blank media being used (they are bad ones), and sometimes burning at less than max speed allows the burn to be "deeper" and can facilitate to be read by other players.
Tip: optical burning is not a permanent process, it changes chemicals on the blank media, but it wears out over time, so don't burn your bank account passwords there thinking you are guaranteed to read it back.