Не вызывается модальное окно?

Доброго времени суток.

Для простой странички нашел решение в виде корзины, вот оно.
Либо так:

​// ************************************************
// Shopping Cart API
// ************************************************

var shoppingCart = (function() {
  // =============================
  // Private methods and propeties
  // =============================
  cart = [];
  
  // Constructor
  function Item(name, price, count) {
    this.name = name;
    this.price = price;
    this.count = count;
  }
  
  // Save cart
  function saveCart() {
    sessionStorage.setItem('shoppingCart', JSON.stringify(cart));
  }
  
    // Load cart
  function loadCart() {
    cart = JSON.parse(sessionStorage.getItem('shoppingCart'));
  }
  if (sessionStorage.getItem("shoppingCart") != null) {
    loadCart();
  }
  

  // =============================
  // Public methods and propeties
  // =============================
  var obj = {};
  
  // Add to cart
  obj.addItemToCart = function(name, price, count) {
    for(var item in cart) {
      if(cart[item].name === name) {
        cart[item].count ++;
        saveCart();
        return;
      }
    }
    var item = new Item(name, price, count);
    cart.push(item);
    saveCart();
  }
  // Set count from item
  obj.setCountForItem = function(name, count) {
    for(var i in cart) {
      if (cart[i].name === name) {
        cart[i].count = count;
        break;
      }
    }
  };
  // Remove item from cart
  obj.removeItemFromCart = function(name) {
      for(var item in cart) {
        if(cart[item].name === name) {
          cart[item].count --;
          if(cart[item].count === 0) {
            cart.splice(item, 1);
          }
          break;
        }
    }
    saveCart();
  }

  // Remove all items from cart
  obj.removeItemFromCartAll = function(name) {
    for(var item in cart) {
      if(cart[item].name === name) {
        cart.splice(item, 1);
        break;
      }
    }
    saveCart();
  }

  // Clear cart
  obj.clearCart = function() {
    cart = [];
    saveCart();
  }

  // Count cart 
  obj.totalCount = function() {
    var totalCount = 0;
    for(var item in cart) {
      totalCount += cart[item].count;
    }
    return totalCount;
  }

  // Total cart
  obj.totalCart = function() {
    var totalCart = 0;
    for(var item in cart) {
      totalCart += cart[item].price * cart[item].count;
    }
    return Number(totalCart.toFixed(2));
  }

  // List cart
  obj.listCart = function() {
    var cartCopy = [];
    for(i in cart) {
      item = cart[i];
      itemCopy = {};
      for(p in item) {
        itemCopy[p] = item[p];

      }
      itemCopy.total = Number(item.price * item.count).toFixed(2);
      cartCopy.push(itemCopy)
    }
    return cartCopy;
  }

  // cart : Array
  // Item : Object/Class
  // addItemToCart : Function
  // removeItemFromCart : Function
  // removeItemFromCartAll : Function
  // clearCart : Function
  // countCart : Function
  // totalCart : Function
  // listCart : Function
  // saveCart : Function
  // loadCart : Function
  return obj;
})();


// *****************************************
// Triggers / Events
// ***************************************** 
// Add item
$('.add-to-cart').click(function(event) {
  event.preventDefault();
  var name = $(this).data('name');
  var price = Number($(this).data('price'));
  shoppingCart.addItemToCart(name, price, 1);
  displayCart();
});

// Clear items
$('.clear-cart').click(function() {
  shoppingCart.clearCart();
  displayCart();
});


function displayCart() {
  var cartArray = shoppingCart.listCart();
  var output = "";
  for(var i in cartArray) {
    output += "<tr>"
      + "<td>" + cartArray[i].name + "</td>" 
      + "<td>(" + cartArray[i].price + ")</td>"
      + "<td><div class='input-group'><button class='minus-item input-group-addon btn btn-primary' data-name=" + cartArray[i].name + ">-</button>"
      + "<input type='number' class='item-count form-control' data-name='" + cartArray[i].name + "' value='" + cartArray[i].count + "'>"
      + "<button class='plus-item btn btn-primary input-group-addon' data-name=" + cartArray[i].name + ">+</button></div></td>"
      + "<td><button class='delete-item btn btn-danger' data-name=" + cartArray[i].name + ">X</button></td>"
      + " = " 
      + "<td>" + cartArray[i].total + "</td>" 
      +  "</tr>";
  }
  $('.show-cart').html(output);
  $('.total-cart').html(shoppingCart.totalCart());
  $('.total-count').html(shoppingCart.totalCount());
}

// Delete item button

$('.show-cart').on("click", ".delete-item", function(event) {
  var name = $(this).data('name')
  shoppingCart.removeItemFromCartAll(name);
  displayCart();
})


// -1
$('.show-cart').on("click", ".minus-item", function(event) {
  var name = $(this).data('name')
  shoppingCart.removeItemFromCart(name);
  displayCart();
})
// +1
$('.show-cart').on("click", ".plus-item", function(event) {
  var name = $(this).data('name')
  shoppingCart.addItemToCart(name);
  displayCart();
})

// Item count input
$('.show-cart').on("change", ".item-count", function(event) {
   var name = $(this).data('name');
   var count = Number($(this).val());
  shoppingCart.setCountForItem(name, count);
  displayCart();
});

displayCart();

Всё прекрасно интегрировал на свою страничку для теста. Работает всё, кроме вызова модального окна, то есть самой корзины.



В моей "голове" всё так:

<head>
	<meta charset="UTF-8">
	<meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no">
	<title>Sporttech - Опт / Розница</title>

	<!--Подключение классов-->
	<link rel="shortcut icon" href="material.png" type="image/x-icon">

	<link href="https://fonts.googleapis.com/css?family=Oswald:400,500,600,700&display=swap&subset=cyrillic"
		rel="stylesheet">
	<link rel="stylesheet" href="https://use.fontawesome.com/releases/v5.6.3/css/all.css"
		integrity="sha384-UHRtZLI+pbxtHCWp1t77Bi1L4ZtiqrqD80Kn4Z8NTSRyMA2Fd33n5dQ8lWUE00s/" crossorigin="anonymous">
	<link rel="stylesheet" href="/libs/jquery.scrollbar-gh-pages/jquery.scrollbar.css">
	<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/magnific-popup.js/1.1.0/magnific-popup.css" type="text/css" media="screen" />
	<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/fancybox/3.5.7/jquery.fancybox.min.css"
		type="text/css" media="screen" />
        <link rel="stylesheet" href="/css/libs.min.css">
	<link rel="stylesheet" href="/css/main.css">
</head>

Секция скриптов внизу документа:

<!--Scripts Section-->
	<script>
		var video = document.getElementById("fullvideo");
		var btn = document.getElementById("myBtn");
		function myFunction() {
			if (video.paused) {
				video.play();
				btn.innerHTML = "Пауза";
			} else {
				video.pause();
				btn.innerHTML = "Продолжить";
			}
		}
	</script>

	<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.2.4/jquery.min.js"></script>
	<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.9/umd/popper.min.js"
		integrity="sha384-ApNbgh9B+Y1QKtv3Rn7W3mgPxhU9K/ScQsAP7hUibX39j7fakFPskvXusvfa0b4Q"
		crossorigin="anonymous"></script>
	<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery.mask/1.14.15/jquery.mask.js"></script>
	<script src="libs/jquery.scrollbar-gh-pages/jquery.scrollbar.js"></script>
	<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/magnific-popup.js/1.1.0/jquery.magnific-popup.js"></script>
	<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/fancybox/3.5.7/jquery.fancybox.min.js"></script>
	<script src="js/shopcard.js"></script>
	<script src="js/common.js"></script>

Чтобы я ни делал, не заводится. И не могу найти ошибку, тысяча чертей.
Можете глупого ткнуть носом, либо подсказать, куда копать?