input->set_cookie or setcookie not work

[eluser]helloworld7[/eluser]
Hi. I'm having problem with setting cookies using the input set_cookie or the php setcookie function.

It doesn't have any errors on the page but when I print the cookie using input->cookie() or just $_COOKIE then all I can see is just the php session id.

Array ( [PHPSESSID] => spib39ei0c4u7k9mk8ir464uc7 )

I'm added the native session class but it shouldn't affect it?

I don't know how to troubleshooting this. Where should I check? Any help will be appreciated.

Thanks.