Bug in VS redirect with HTML iRule?

when HTTP_REQUEST {
    if { [active_members [LB::server pool]] < 1 } {
    log local0. "Client [IP::client_addr] requested Host: [HTTP::host] with URI: [HTTP::uri] accessed [virtual] but no active nodes available..."

        switch [HTTP::uri] {
            "/Logo.png" {
                                HTTP::respond 200 content [ifile get "Logo.png"] "Content-Type" "image/png" "Cache-Control" "no-cache, must-revalidate"
                                }
        default { 
                    HTTP::respond 503 content {




Error 503 Service Unavailable


 Service Unavailable 
The server is temporarily unable to service your request due to maintenance downtime or capacity problems. Please try again later.



        }
      }
    }
  }
}