How to track checkout stages in ec analitycs?

Question

Google

Hello everyone
. I want to send a step when clicking on the button in the eCommerce section Behavior during registration in the analytics. I followed this example
https://developers.google.com/analytics/devguides/... Checkout
process > Payment
But nothing is transferred, what could be the problem? Need something else to add? Thanks in advance for your reply!

<script>
ga('create', 'UA-105680803-1');
ga('require', 'ec');

function checkout(cart) {
  for(var i = 0; i < cart.length; i++) {
    var product = cart[i];
    ga('ec:addProduct', {
      'id': 'test2_000',
      'name': 'test2',
      'price': '10',
      'quantity': 1
    });
  }
}


ga('ec:setAction','checkout', {
    'step': 1,            
    'option': 'r_test_step_1'     
});
ga('send', 'pageview'); 
</script>