Cookie is not deleted js

Question

I use this code to delete a cookie:

function deleteCookie(name) {
  document.cookie = name +'=; Path=/; Expires=Thu, 01 Jan 1970 00:00:00 UTC;';
}

cookieName = "gdeslon.kokoc.com.__arc_aid";
deleteCookie(cookieName);

But this code does not delete a cookie:

What could be the reason for the code not working?