Carbon::createFromDate Date Of Birth Saving Null In DB

I have 3 select drop downs day, month, year when submitted I get 1992 12 10 I then use carbon to create date from and try and save it with my model but when I check the DB the dob is null, the field type is DATE

$dob = Carbon::createFromDate($request->birthday_year, $request->birthday_day, $request->birthday_month); $profile = new Profile; $profile->user_id = $user->id; $profile->dob = $dob;