sender's ip address

[xoxLISAxox]

IN PHP:

$useripaddy = $_SERVER['REMOTE_ADDR']; 

Very simple form email. When we receive it, we would like to show the ip address of the sender, to keep for our records. The above is not working, it show's our ip address instead of the sender. How do I fix this? It's on a secure https, it make a difference?

Thank you