LTM log tmm errors "err tmm9[22715]: 012200001:3: TCL error"

Hi everyone, we implemented an iRule and we received on the LTM the following "log errors":

"Feb 22 12:18:47 slot2/device1 err tmm2[22850]: 01220001:3: TCL error: /Common/in_house_iRuletcp-rule - can't read "detect_handshake": no such variable while executing "if { ($detect_handshake) } { skip past the session id set record_offset 43 binary scan [TCP::payload] @${record_..."

Where the iRule define the variable "detect_hadshake":

binary scan [TCP::payload] 
if { [binary scan [TCP::payload] cSS tls_xacttype tls_version tls_recordlen] < 3 } { 
  reject return 
} 
# XX8 SSLv3.0 XX9 TLSv1.0 XX0 TLSv1.1 XX1 TLSv1.2 
switch $tls_version { 
  "XX9" - 
  "XX0" - 
  "XX1" { 
    if { ($tls_xacttype == 22) } {
      binary scan [TCP::payload] @5c tls_action 
      if { not (($tls_action == 1) && ([TCP::payload length] > $tls_recordlen)) } {
        set detect_handshake 0 
      } 
    } 
  } 
  "XX8" { 
    set detect_handshake 0 
  } 
  default { 
    set detect_handshake 0 
  } 
} 
if { ($detect_handshake) } { 
  # skip past the session id 
  set record_offset 43 
  binary scan [TCP::payload] @${record_offset}c tls_sessidlen 
  set record_offset [expr {$record_offset + 1 + $tls_sessidlen}]

Can somebody help me?

Thanks

CB