Why won't my lightscribe cd-r play in cd players?

(I'm running Windows Vista) I have a new (1x3) Lightscribe duplicator. I burned a regular blank CD-R from the playlist on my computer. My tracks were all mp3 in Real Player, until I placed them into Windows Media Player. Windows Media PLayer automatically converted them to wma. After my duplicator copies completed successfully, I injected one of the Lightscribe copies into a small Sony CD player, but instead of playing it, the screen said... "DATA." In other players, the Lightscribe copy doesn't say (or do) anything. The CD-R master I burned Lightscribe copies from is: MEMOREX - 52X - 700MB - 80min. Can anyone tell me why I'm having this problem, and what I can do to fix it?