Some of my music wont play please help

I everyone ,

Having recently bought my iPad 3 I synced my iTunes transferring all my music on to my iPad using my laptop around 2000 songs not alot really ,and some (not all) of my music will not play on my iPad I assume that all the music is in the correct format as it all plays in iTunes and ipods no problems I have tried syncing again and doing it all over again.
Thought I would seek some advice from some experts being relatively new to apple products .

Many thanks

Debs