Custom Sync - Indicates it is but no transfer

Have iMac G5, wireless connection to ATV which has high connection signal, can successfully view movie trailers (inc HD) however, when syncing with my iTunes, it indicates at the top it is "syncing Apple TV" with the diagonal white and dark lines - but nothing more. This is the case also with automatic sync,or different combinations of custom sync. My main library in ATV is the iTunes and is linked, any other suggestions?