Cookies in frames with different domains

Hi all, I am trying to use a cookie on the now popular "stealth redirect" method which involves having a frame encapsulate another URL. For reference, I have www.domain1.com point to a file called index.htm. In index.htm, it just has two frames. The first frame points to www.domain2.com/subdir as the "source" (src) and the 2nd frame (invisible) points to a blank html file. When I use cookies like this: setCookie("Username",$username,time()+(3600*24*365),"/"); it works when my browser points to www.domain2.com/subdir. However, when I go to www.domain1.com, it doesn't work anymore (even if I set the cookie again, it doesn't display). Any ideas? I have tried using: setCookie("Username",$username,time()+(3600*24*365),"/",".domain1.com"); and setCookie("Username",$username,time()+(3600*24*365),"/",".domain2.com"); with no luck. Thanks, Chris