I have an new Iphone 5 that will not restore from Itunes?

I bought a new Iphone 5 and wanted to restore all of my settings from a previous Iphone 4S that were backed up onto Itunes. However when I plug the phone it, Itunes asks me how I want to set up my phone (as new or from back up), I choose back up and it reverts back to the same page after downloading all of the settings onto the phone! This means I can't sync any content onto the phone at all because it hasn't registered that it's been restored!! Help anyone?