Q: iPhone 5s set-up from iTunes back-up

I just did a back-up to itunes from my iPhone 4 and when attempting to set up my iPhone 5s via back-up vs. a new device it's asking for a password to unlock the backup data.  I tried my iTunes password, but that does not work and when conducting the backup process iTunes never asked for a "back-up" password.  How do I unlock so I can get my new iPhone 5s set-up. 

Thanks!