Q: Cant update Lion to Sierra

I have a Macbook Pro  OS X Lion 10.7.5.  In the app store I cant download Sierra. Ive backed up my computer and Ive also restarted in recovery mode and done a disk repair.  The disk is perfect.  Still cant download.  Do I need to go to an older version first? If my computer runs fine now, do I really need to install any other operating system?

Anything you guys suggest would be much appreciated.