Laravel5.1 jsValidation Unique rule issue

I'm using laravel-jsValidation, everything is working fine except Unique rule ! Here what I have : Rules :

protected $userValidate=[
          'lastname' => 'required|max:100|min:2',
          'firstname' => 'max:100|min:2',
          'username' => 'required|unique:users|min:2',
          'email' => 'required|unique:users|email|max:255',
          'password' => 'required|confirmed|min:6',  ];

Get Users List Function :

public function getUsers(){
  $validator = JsValidator::make($this->userValidate);      
  return view('admin.usersList')->withValidator($validator);}

Store Function :

public function store(Request $request){   
  $data = $request->all();

  $v = Validator::make($data, $this->userValidate);           

  if ($v->fails())
  {
      return redirect()->back()->withErrors($v->errors());          
  }  

  $user = User::create([
        'lastname' => $data['lastname'],
        'firstname' => $data['firstname'],
        'username' => $data['username'],
        'email' => $data['email'],                        
        'password' => bcrypt($data['password']), 
        'confirmed' => 1,                 
    ]);       

  return redirect('admin/usersList');}

The problem is when I enter username or email, an error message appears under its input in form:

Whoops, looks like something went wrong.

NB : I set : 'disable_remote_validation' => false, and when I change it to true, it works fine only if I enter username and email which don't exist in users table !

What's the mistake in my code ?

via Chebli Mohamed