Issues with deleting cookies!?

I'm having issues with my logout system. It's really strange.... the logout page, which deletes the cookie with this:

setcookie("account", null, 1);

will destroy the cookie.... usually. Here's the catch - if it's the first time the user has been to the site, it won't log them out. They have to manually delete the cookie, THEN it will work normally.

What's the deal here? Any suggestions would be great.

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Let me clarify the problem, or you can check it out yourself (sbboard.com/auslander/home.php.... still in development!).

I go onto it from a computer that's never been there, and it doesn't work. The logout page loads, and follows the redirect, but doesn't delete the cookie.

I go and delete my cookies, then I can log in and out millions of times without problem. What's the deal here?

I've also tried this:

session_start();

setcookie("account", session_id(), 1, '/');

session_destroy();

header( 'Location: http://www.sbboard.com/auslander/home.ph... ');

To no avail....

Issues with deleting cookies!?windows live

mine does that too i dont know what to do sorry