WPURP_Template_Recipe_Servings_Changer – in custom template not working

Hello

I’m trying to make a custom template using the functions.php file.
I’ve added all the things I want, but when I added:

<?php
	$recipe_changer = new WPURP_Template_Recipe_Servings_Changer();
	echo $recipe_changer->output( $recipe );
?>

The value is showed, but when I press to change the servings, the values of the ingredients, doesn’t change.

I added this code to show the ingredients.

<?php
	$ingredient_list = new WPURP_Template_Recipe_Ingredients();
	echo $ingredient_list->output( $recipe );
?>

Do I need to add somethins else in order to work with the servings changer?

https://wordpress.org/plugins/wp-ultimate-recipe/