note 9372 added to setcookie

hi, i am working on win2k with php4... whenever i set a Cookie n i chk it on the next page it says "Warning: Undefined variable: Auth in D:\work\shop\menu.php3 on line 2 " where Auth is the cookie i am setting (SetCookie("Auth", 1);) it used to work earlier fine on my win95 with php3 release... can u tell me what could be the problem... this happens only when i am chking my progs on the local machine... http://www.php.net/manual/function.setcookie.php