title: Changing the Add To Cart button text in WooCommerce for items with variations
body: <p>I'm running WooCommerce version 2.5.5. The following lines of code don't seem to change the Add To Cart button text on my product page for an item with variations: </p>
  
  <pre><code>add_filter('variable_add_to_cart_text', 'my_custom_cart_button_text');
  
  function my_custom_cart_button_text() {
  
          return __('Buy Now', 'woocommerce');
  
  }
  </code></pre>
  
  <p>Would you happen to know what I'm missing?</p>