I see the solution:

Аdd to cart in this module works through a controller
/catalog/controller/checkout/cart.php

  public function addCombo() {
    $this->language->load('checkout/combo');

    $json = array();

    if (isset($this->request->post['combo_id'])) {
      $combo_id = $this->request->post['combo_id'];
    } else {
      $combo_id = 0;
    }

    if (isset($this->request->post['combo_quantity'])) {
      $combo_quantity = $this->request->post['combo_quantity'];
    } else {
      $combo_quantity = 1;
    }

    if (isset($this->request->post['option'])) {
      $post_option = array_filter($this->request->post['option']);
    } else {
      $post_option = array();
    }

    $this->load->model('catalog/combo');

    $ps = $this->model_catalog_combo->getComboProducts($combo_id);

    $this->load->model('catalog/product');

    $add_data = array();

    foreach($ps as $p) {
      $product_info = $this->model_catalog_product->getProduct($p['product_id']);
      if ($product_info) {
        $option = array();

        $product_options = $this->model_catalog_product->getProductOptions($p['product_id']);

        foreach ($product_options as $product_option) {

          if ($product_option['required'] && empty($post_option[$product_option['product_option_id']])) {
            $json['error']['option'][$product_option['product_option_id']] = sprintf($this->language->get('error_required'), $product_option['name']);
            $json['error']['combo_id'] = $combo_id;
          } else if (!empty($post_option[$product_option['product_option_id']])){
            $option[$product_option['product_option_id']] = $post_option[$product_option['product_option_id']];
          }
        }

        $add_data[] = array (
          'product_id' => $p['product_id'],
          'quantity' => $p['quantity'],
          'option' => $option,
        );
      }
    }

    if (!$json) {
      $quantity = 0;
      foreach($add_data as $add)
      {
        $this->cart->add($add['product_id'], $combo_quantity * $add['quantity'], $add['option']);
        $quantity += $combo_quantity * $add['quantity'];
      }

      $json['success'] = sprintf($this->language->get('text_success'), $quantity, $this->url->link('checkout/cart'));

      unset($this->session->data['shipping_method']);
      unset($this->session->data['shipping_methods']);
      unset($this->session->data['payment_method']);
      unset($this->session->data['payment_methods']);

      // Totals
      $this->load->model('setting/extension');

      $total_data = array();
      $total = 0;
      $taxes = $this->cart->getTaxes();

      // Display prices
      if (($this->config->get('config_customer_price') && $this->customer->isLogged()) || !$this->config->get('config_customer_price')) {
        $sort_order = array();

        $results = $this->model_setting_extension->getExtensions('total');

        foreach ($results as $key => $value) {
          $sort_order[$key] = $this->config->get($value['code'] . '_sort_order');
        }

        array_multisort($sort_order, SORT_ASC, $results);

        foreach ($results as $result) {
          if ($this->config->get($result['code'] . '_status')) {
            $this->load->model('total/' . $result['code']);

            $this->{'model_total_' . $result['code']}->getTotal($total_data, $total, $taxes);
          }

          $sort_order = array();

          foreach ($total_data as $key => $value) {
            $sort_order[$key] = $value['sort_order'];
          }

          array_multisort($sort_order, SORT_ASC, $total_data);
        }
      }

      $json['total'] = sprintf($this->language->get('text_items'), $this->cart->countProducts() + (isset($this->session->data['vouchers']) ? count($this->session->data['vouchers']) : 0), $this->currency->format($total));
    } else {
      $json['error']['warning'] = $this->language->get('text_error');
      $json['redirect'] = str_replace('&', '&', $this->url->link('product/combo', 'combo_id=' . $json['error']['combo_id']));
    }

    $this->response->setOutput(json_encode($json));
  }

catalog\view\theme\shoppica2\template\module\combo.tpl

function addComboToCart(id) {
  $('input[name=combo_id]').val(id);
  $.ajax({
    url: 'index.php?route=checkout/cart/addcombo',
    type: 'POST',
    data: $('.product-info input[type=\'text\'], .product-info input[type=\'hidden\'], .product-info input[type=\'radio\']:checked, .product-info input[type=\'checkbox\']:checked, .product-info select, .product-info textarea'),
    dataType: 'json',
    success: function(json) {
      $('.success, .warning, .attention, .information, .error').remove();

      if (json['error']) {
        if (json['error']['product_id'] != <?php echo $product_id?>) {
          location = json['redirect'];
        }
        if (json['error']['option']) {
          for (i in json['error']['option']) {
            $('#option-' + i).after('<span class="error">' + json['error']['option'][i] + '</span>');
          }

          $('#notification').html('<div class="warning" style="display: none;">' + json['error']['warning'] + '<img src="catalog/view/theme/default/image/close.png" alt="" class="close" /></div>');

          $('.warning').fadeIn('slow');

          $('html, body').animate({ scrollTop: 0 }, 'slow');

        }
      }

      if (json['success']) {
        $('#notification').html('<div class="success" style="display: none;">' + json['success'] + '<img src="catalog/view/theme/default/image/close.png" alt="" class="close" /></div>');

        $('.success').fadeIn('slow');

        $('#cart-total').html(json['total']);

        $('html, body').animate({ scrollTop: 0 }, 'slow');
      }
    }
  });
}

but it does not work.
Looked like to put in a Shopping Cart in the product template
/catalog/view/theme/shoppica2/template/product/product.tpl

there use

url: ‘index.php?route=tb/cartCallback’,

The search led me to:
/tb_themes/shoppica2/catalog/controller/TbController.php
on line 62:

    public function cartCallback()
    {
        $this->response->setOutput(json_encode($this->getCartContents()));
    }

and

line 141
public function getCartContents()
{
. . . . .


You can try to open catalog/view/theme/shoppica2/javascript/common.js.php and search for function addToCart(product_id). Inside this function you could replace

url: 'index.php?route=tb/cartCallback',

url: 'index.php?route=checkout/cart/addcombo',

See if this works.

Regards,
ThemBurn team

up!

have you solve this problem?
because i have this problem too..