Ошибка с collapse на codeigniter

этот кодь не работает. Как я могу исправит?

        <?php $tour_category = FALSE; ?>
    <div class="card shadow">
        <a href="<?=base_url().LANG?>/tours.html"><h4 class="card-header bg-warning"><?=lang('widget_tours_categories')?></h4></a>
        <?php $i = 0; ?>
        <div class="card">
        <?php foreach ($tours as $tour) : ?>
            <?php if ($tour['tour_category_name'] != $tour_category) : ?> 
            <?php $tour_category = $tour['tour_category_name']; ?>
                <div class="card-header">
                <a href="<?=base_url().LANG?>/tours/category/<?=$tour['tour_category_url']?>.html"><?=$tour['tour_category_name']?></a>
                <div class="float-right" id="headingOne" type="button" data-toggle="collapse" data-target="#collapseOne<?=$tour['tour_category_id']?>" aria-expanded="false" aria-controls="collapseOne">
                            <ion-icon name="ios-arrow-down" size="small"></ion-icon>
                </div>
                </div>
            <?php $i = 0; ?>
            <?php endif; ?>
                    <div class="list list-danger">
            <?php if ($i < 15) : ?>
                <div id="collapseOne<?=$tour['tour_category_id']?>" class="collapse" aria-labelledby="headingOne" data-parent="#accordionExample">
                        <p class="border-bottom cat-page"><a href="<?=base_url().LANG?>/tours/<?=$tour['url']?>.html"><?=$tour['name']?></a> <span class="text-muted">(<?=$tour['days']?> days)</span></p>
                    </div>
            <?php endif; ?>
        <?php $i++; ?>
                </div>
        <?php endforeach; ?>
        </div>
    </div>