Why my iPhone sync incompletely with iTunes

Posted changes to iTunes on MacBookPro, hit Sync, got message "couldn't sync" due to too much space required for added tracks, even though memory-bar indicated enough freespace; removed apps from iPhone to create space, subsequently failed to sync once again.  Powered phone down, then up, and repeated; sync added new items, but didn't link them correctly by artist and genre.  Am I doing something incorrectly, or does this process need a thorough going-over by SQA? 

Billy