why are my iphone backups on icloud greyed out so i cannot select them?

I got a new iphone 4s today after a fault with my 10month old on/off button stopped working. I backed up my icould 2 minutes before i swapped the phone which was successful. I got my new phone and turned it on, went through the set up assistant but when i tried to restore it from icloud i got a list of 3 recent back ups including my one i did in store but they are greyed out and a message stating 'No icloud backups are compatible with the version of iOS (6.0.1) on this iphone'