Test the ISO file on your computer and see if it will play there. VLC media player can play ISO movie files directly. www.videolan.org
If the ISO plays with no problems, then you may have something else going on. Check to see if the disk you burned plays in the computer.
Poor media, too fast a burn, picky dvd player...all could come into play as a reason the disk isn't working on the stand alone dvd player.