Custom post type navigation : get posts from all site

Hello,
I’ve created a custom post type called wednesdayshot, a template page which shows all posts with thumbnails, when I click on one, I get the single page of that post (using single-wednesdayshot.php). The thing is : I want to add to this single page a navigation so I added “previous_post_link()” and “next_post_link()” to my template, but the only link I get is the first post I published in the entire website, not the previous post of that custom post type. I don’t find anyone who have this issue in any forums so I suppose I do something wrong but what?

Your ideas are welcome.