Problems restoring iPad mini from backup

Hi

A friend of mine recently developed a fault with the screen on his iPad mini resulting in Apple replacing the iPad mini with a new one. Before they did this I advised him to backup his iPad so that in this event he would be able to restore his apps/settings etc to the way it was. A full backup was done the night before the iPad was taken into Apple and replaced.

When the new iPad was plugged in and restored from the most recent back up (which is the one taken the night before the iPad was replaced) it hasn't restored anything from the old iPad - no music/apps or photos but seems to have restored some things from his old iPhone. Not sure whether this makes a difference but the old iPad was iOS6 and the new one is running iOS7 - I wouldn't have thought this would make a difference but
Unsure why else the new iPad isn't restoring correctly so would be grateful if anyone has any suggestions??