itunes not able to capture my latest iphone backup on pc

i am using version 12.7.1.14 itunes on my pc.

I backup my iphone (version 11.1) on Nov 16, 2017, however itunes shows that my latest backup was Dec 13, 2016.

When I open \Users\(username)\AppData\Roaming\Apple Computer\MobileSync\Backup on my pc, the Nov 16, 2017 file is sitting in there with full content.

Please advise how I may connect my latest backup with itunes.

Thanks a lot!

eliza