cannot copy songs from my itunes to my wife's iphone

Hello,

My family uses one laptop which has iTunes loaded on it with all my songs (about 5000). I have al old iPod (30G from about 6 years ago) which is synced to iTunes - and I don't have an iPhone. My wife has an iPhone and occassionally she wants to copy songs from iTunes to her iPhone. We have managed to do this in the past (e.g. last year), but now we can't. She recently received 3 digital files (all approx 54 minutes in length) which I uploaded into iTunes. The problem is wqe cannot move or copy these into her iPhone, despite spending hours trying to do so! I have connected her iPhone, selected 'only sync ticked songs' and then unticked everything EXCEPT the 3 songs she wants. Regardless of what we try the songs will not copy across. Please help. Thanks,

Gerry Davis