Laravel 5.2 - Mutators - SetAttribute

I'm using Laravel 5.2

I have the next mutator in Information's Model.

User Model has "Information" and "Information" has "User"

public function setMyDateAttribute($value){
      $this->attributes['my_date'] = \Carbon\Carbon::createFromFormat('d-m-Y', $value);
}

And

$user->information()->update($request->get('information'));

But nothing happens...

But if I do:

$information = $request->get('information');
$information['my_date'] = \Carbon\Carbon::createFromFormat('d-m-Y', $information['my_date']);
$user->information()->update($information);

it works perfect

What I'm missing?

Thanks

via Chebli Mohamed