Songs disappeared from phone and won't resync

I bought an album on my phone, then synced it to my computer. All the songs are on my itunes and play perfectly on the computer, and according to itunes they're all on my phone, but the first 2 songs on the album don't appear on my phone, and if I go to itunes on my phone I can't play them, it wants me to buy them again (all the other songs in the album say 'play').

I've tried restarting the phone, removing the album from my phone, resyncing it, syncing a playlist with just the 2 songs, however none of it works - the playlist with just the 2 songs comes up on my phone as blank. Help please???