01220001:3: TCL error: wrong # args: should bewhile executing

The catch command runs the command inside it. So you don't need to run it again. Can you try this?

 
 when HTTP_RESPONSE {   
    if { [HTTP::cookie exists "LBSICAPRENDE"] } {   
       if {[catch {persist add uie [HTTP::cookie "LBSICAPRENDE"]} result]}{   
          log local0. "[IP::client_addr]:[TCP::client_port]:\ 
             Error on response from [IP::server_addr] with cookie [HTTP::cookie LBSICAPRENDE]. \$result: $result."   
       }   
    }   
 }   
 

Also, I'm not sure why you're only adding a persistence record once per TCP connection. If multiple clients connect from behind the same proxy, they could share the same TCP connection. You'd want to set the persistence for both clients.

Aaron