For newly added posts you have to go to the "new" page and upvote from there. If you're passing around a link to the direct post to get upvotes you're assumed t

For newly added posts you have to go to the "new" page and upvote from there. If you're passing around a link to the direct post to get upvotes you're assumed to be part of a voting ring and your votes are ignored with respect to being promoted to the home page.