mp4 Movies Won't Sync

I recently tried to upload a new mp4 movie onto my iPhone, but iTunes ended up removing the mp4 movie I already had on there and now won't sync either of the 2 movies? I have tried syncing one at a time or both at the same time, but it still won't sync.

The total file size for the 2 movies is 2.8 GB, but it shows that I have 3.8GB free on my iPhone.

I downloaded the newest iTunes update, Quicktime, and also reboot my iPhone, but nothing works.