I also had similar problems with Ipad air not restoring ipad2 backup. I went to Apple and for the sake of not pre empting negative discussion will leave that at that.
Found my answer in google and I hope it helps someone else.
Turned off virus protection. Ipad air restored backup. Yey.
HHow was the problem solved
i bought a iPad air 2 and am not able to retire from my old iPad 2 back up
sshall be grateful if you can help
Retrieving data ...