Audio files not found?

It's my first time syncing music files to my Ipad 3rd generation through Itunes. It played well at start and I removed the music files through syncing

Then I looked at the ratio of used data space of my Ipad through Itunes and found that there's still 34 songs (or 1.41 GB) in the audio section, then I looked at the Settings/General/About tab in my Ipad and found that there aren't any song in my Ipad. I even double checked in the Music application of the Ipad itself, and there's no music files.