so I transferred a whole bunch of songs/tracks over to my ipod touch...but when i turn the touch sideways to browse through my tracks in coverflow, I see only about 4 tracks having an "album cover preview". All of the others just have a gray box with a question mark. I can still listen to those songs, but I'd like to have that "album cover preview" so that I can browse using coverflow. Any ideas how to fix this?