Burned music will not play on portable

How do I guarantee that the music I download off of the internet onto CD-R’s will work when played in car stereo, portable radio, etc? I burned some music and it plays fine on DVD player, computer, and stereo, but will not work in car stereo or portable radio. What do I do during the burn method to insure it works for everything. I use NERO and TDK digital mixmaster.