Are you logged in while trying to access the page? Editors still have access to expired content. Archiving a page only means it's moved to another location.
Try to expire a page and then access it anonymoulsy, either with a new browser session or in private/incognito mode.
I am facing a strange issue in my website. When I set a page to exprire using Manage Expiration and Archiving tab. The page is still acessable in the browser. The moment i delet the page then its inaccessible. Any ideas how can i fix it?