Persistence Cookie iRule not working as desired

[root@iris:Active] config  b virtual bar list
virtual bar {
   snat automap
   pool foo
   destination 172.28.17.33:http
   ip protocol tcp
   rules myrule
   persist cookie
   profiles {
      http {}
      tcp {}
   }
}
[root@iris:Active] config  b pool foo list
pool foo {
   members 10.10.70.110:http {}
}
[root@iris:Active] config  b profile cookie list
profile persist cookie {
   mode cookie
   mirror disable
   cookie mode insert
   cookie name none
   cookie expiration immediate
   cookie hash offset 0
   cookie hash length 0
   rule none
}
[root@iris:Active] config  b rule myrule list
rule myrule {
   when HTTP_REQUEST {
        persist cookie insert "cookieirule"
}
}

[root@iris:Active] config  curl -I http://172.28.17.33/
HTTP/1.1 200 OK
Date: Wed, 02 Nov 2011 08:50:42 GMT
Server: Apache/2.0.59 (rPath)
Last-Modified: Sat, 11 Jun 2011 00:31:47 GMT
ETag: "667a-67-cfb682c0"
Accept-Ranges: bytes
Content-Length: 103
Vary: Accept-Encoding
Content-Type: text/html; charset=UTF-8
Set-Cookie: cookieirule=1850083850.20480.0000; expires=Wed, 02-Nov-2011 17:43:31 GMT; path=/