CodeShare Refresh: HTTP Session Limit

I tried, the irule above with some modications to it, but I can get the counter to display i see on the logs files the below

Thu Oct 18 14:50:40 CAT 2018 err bigip1 tmm[12118] 01220001 TCL error: /Common/qasessionlimitv1 - can't read "countsessions": no such variable while executing "HTTP::respond 200 content "$countsessions"

HERE IS MY IRULE I USED, any help guys ?

when RULE_INIT { set static::max_active_clients 1 log local0. "rule session limit reached"

when HTTP_REQUEST {
   test cookie presence
  if {[HTTP::cookie exists "ClientID"]} {
    set need_cookie 0
    set client_id [HTTP::cookie "ClientID"]
    if cookie not present & connection limit not reached, set up client_id
   if { [HTTP::uri] eq "/counter"} { HTTP::respond 200 content "$countsessions"}
 } else {
   if {not ([table keys -subtable httplimit] > $static::max_active_clients)} {
     set need_cookie 1
     set client_id [format "%08d" [expr { int(100000000 * rand()) }]]
      Only count this request if it's the first on the TCP connection
     if {[HTTP::request_num] == 1}{
       table set -subtable httplimit [IP::client_addr]:[TCP::client_port] "blocked"
       set countsessions [table keys -subtable $httplimit -count]
      set timer [after 60000 -periodic { table lookup -subtable httplimit [IP::client_addr]:[TCP::client_port] }]
     }





   } else {

    HTTP::respond 200  content { 

    
    
    
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    }
  }
 } 

}

when HTTP_RESPONSE { insert cookie if needed if {$need_cookie == 1} { HTTP::cookie insert name "ClientID" value $client_id path "/" } }