I cannot backup my phone.

Hi. im switching from iPhone 4 to an iphone 5.

my last backup of iphone 4 was in nov 13. so obviously its been a while. now when i try to sync it to my computer (Win 7), i plug it in but iTunes does not let me backup. it only gives me an option to RESTORE FROM BACKUP or SETUP AS A NEW PHONE.

i have the latest itunes and the iphone software.

i have attached a couple of snaps.

backup option under Devices is also greyed out.

any help would be grateful

thanks