Why won't some of the songs I synced won't appear on my Sansa Fuze?

Four of the songs I downloaded onto Windows Media Player won’t show up oon my MP3 even after they were supposivly SYNCED onto it. It downloaded all the song and then synced it but it won’t appear. It’s only four of htem and the other six downloaded right off Walmart. I payed money and I can’t get a refund. How come they won’t come up?
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Help! My Sansa Fuze is weird!

Look for songs/artists/albums listed on your Fuze as “unknown”. Sansas categorize tracks by ID3 tags, not file or folder names, and if the tags aren’t properly filled in your tracks won’t be where you expect them to be. You can use a program like MP3Tag to fill in the missing information.

Same thing happened to me with Amazon.  It didn’t even show up on WMP 11.  I looked in the My Music folder and there was the song.  I then added it to WMP and synced and it synced okay.

When I bought music from Walmart ages ago, it was DRMed (never doing that again), so it may or may not show up on your Fuze AFTER you’ve played it at least once on in WMP. But that’s a maybe, which is part of why I don’t like DRMed stuff.