You need the change the authentication model from the default User.
Your application is using namespaces or you want to use a differently named model for users.
app/config/auth.php to change the model.
Don’t forget the required interfaces.
If you’re using your own model it’s important that your model implements Auth’s UserInterface. If you’re implementing the password reminder feature it should also implement RemindableInterface.
class User extends \Eloquent implements UserInterface, RemindableInterface