Unsetting Cookie won't work ?

I have done this many times before and for some reason the cookie just won't unset or expire ?

session_destroy();
unset($_COOKIE['CPUsername']);
setcookie("CPUsername","",1);
header("Location: index.php");
exit();

For some reason it just won't unset regardless of what I try.

Edit: I just realised once I posted it as to why .. silly me! being a while since doing PHP work.

Any mods who see this if you want to delete it as its sorted now.

Edited September 13, 201411 yr by tomanderson91