Some tracks won't transfer from iTunes to iPhone 5

When syncing my iPhone 5 this evening, I noticed that certain albums are just not transferring to my iPhone. I've made sure that the "Entire music library" box is ticked, and that all my songs in my library are also ticked. I deleted all my music and restored the library - still these albums won't transfer. So I even created three new playlists with these album tracks within them - they won't transfer to my iPhone! Anyone any idea?