Validation Form

Hi,
I have a problem with the validation of the form. that it is an insertion, it works but for the modification, it does not work. here is the code for the model

PHP Code:

'email' => 'required|valid_email|is_unique[employee.email,employee_id,{employee_id}]',
'matricule' => 'required|is_natural|is_unique[employee.matricule,employee_id,{employee_id}]', 


controllers: 

PHP Code:

if($emp->validate($this->request->getPost()) === FALSE) {
   $msg = $emp->errors();
   return redirect()->to(site_url('form'))->with('errors',$msg);
}else{
   $emp->save($this->request->getPost());
} 


and the error on update:

PHP Code:

The email field must contain a unique value.
The matricule field must contain a unique value. 


Thank you.