[HTTP::uri] rewrite fail,help please ,thanks

[root@ve1023:Active] config  b virtual bar list
virtual bar {
   snat automap
   destination 172.28.19.79:80
   ip protocol 6
   rules myrule
   profiles {
      http {}
      tcp {}
   }
}
[root@ve1023:Active] config  b rule myrule list
rule myrule {
   when HTTP_REQUEST {
   set orguri [HTTP::uri]
   log local0. "http uri before modified: $orguri"
   switch -glob [HTTP::uri] {
      "/admin*" {
         set tempuri [HTTP::uri]
         log local0. "temprui before replace is $tempuri"

         set tempuri [string replace $tempuri 0 5 "/manager"]
         log local0. "tempuri after replace is $tempuri"

         HTTP::uri $tempuri
         pool test2
      }
      default {
         pool test1
      }
   }
}

when HTTP_REQUEST priority 501 {
        set newuri [HTTP::uri]
        log local0. "Updated URI in 501: $newuri"
}

when SERVER_CONNECTED {
        log local0. "[IP::client_addr]:[TCP::client_port]|[IP::local_addr clientside]:[TCP::local_port clientside]|$orguri|[LB::server pool]|[IP::remote_addr]:[TCP::remote_port]|$newuri"
}
}
[root@ve1023:Active] config  b pool test2 list
pool test2 {
   members 200.200.200.102:80 {}
}

[root@ve1023:Active] config  cat /var/log/ltm
Apr  5 21:54:49 local/tmm info tmm[4797]: Rule myrule : http uri before modified: /admin123
Apr  5 21:54:49 local/tmm info tmm[4797]: Rule myrule : temprui before replace is /admin123
Apr  5 21:54:49 local/tmm info tmm[4797]: Rule myrule : tempuri after replace is /manager123
Apr  5 21:54:49 local/tmm info tmm[4797]: Rule myrule : Updated URI in 501: /manager123
Apr  5 21:54:49 local/tmm info tmm[4797]: Rule myrule : 172.28.19.80:33410|172.28.19.79:80|/admin123|test2|200.200.200.102:80|/manager123