header('HTTP/1.0 404 Not Found'); not doing anything


I have a 404.php file in my site's main directory and I was using header('Location: 404.php'); for a while until someone said that you should use header('HTTP/1.0 404 Not Found'); instead. So I replaced it with that and then added: ErrorDocument 404 /404.php to my apache config file and restarted the server but it doesn't work.

I tried different variations including ErrorDocument 404 404.php and ErrorDocument 404 mywebite/404.php but to no avail.

What I mean by doesn't work is that earlier when using header('Location: 404.php'); it would redirect to the 404.php file but when I replace it with header('HTTP/1.0 404 Not Found'); it seems to just skip over the line and not do anything. It most certainly is not redirecting. The reason I am calling for the redirect is because if a $_GET header value is not recognized the page should 404.