How come when I put 100 songs on my MP3 player only about 75 show up?

I have a Creative Muvo V100 and am using Windows Vista, which it says is compatible with, and when I sync all my songs onto the player, it says they all were synced, yet when I listen to it they are not all their. I checked Creatives website and cannot find how to get email support from them. It did say it supports mp3's and wma's and I checked and all of mine are mp3's with a bitrate of 128 or higher. What gives??