Navbar dropdown toggle immediately disappears upon click on mobile site. bootstrap 3.3.7

The navbar on my website works well on pc but on mobile. Whenever I toggle the dropdown for my navbar and click on the Log-in/sign up, it appears but disappears immediately.

This is my website: www.krakenro.com This is my code:

<div class="navbar navbar-inverse navbar-fixed-top" role="navigation">
<div class="container">
    <div class="navbar-header">
        <button type="button" class="navbar-toggle" data-toggle="collapse" data-target=".navbar-collapse">
            <span class="sr-only">Toggle navigation</span>
            <span class="icon-bar"></span>
            <span class="icon-bar"></span>
            <span class="icon-bar"></span>
        </button>
        <a class="navbar-brand" href="./"><?php echo Flux::config('SiteTitle'); ?></a>
    </div>
    <div class="collapse navbar-collapse">
        <ul class="nav navbar-nav">
            <?php $menuItems = $this->getMenuItems(); ?>
            <?php if (!empty($menuItems)): ?>
                <?php foreach ($menuItems as $menuCategory => $menus): ?>
                    <?php if (!empty($menus)): ?>
                        <li class="dropdown">
                        <a href="#" class="dropdown-toggle" data-toggle="dropdown"><?php echo htmlspecialchars(Flux::message($menuCategory)) ?> <b class="caret"></b></a>
                        <ul class="dropdown-menu">
                        <?php foreach ($menus as $menuItem):  ?>
                            <li>
                                <a href="<?php echo $menuItem['url'] ?>"><?php echo htmlspecialchars(Flux::message($menuItem['name'])) ?></a>
                            </li>
                        <?php endforeach ?>
                        </ul>
                        </li>
                    <?php endif ?>
                <?php endforeach ?>
            <?php endif ?>

            <?php $adminMenuItems = $this->getAdminMenuItems(); ?>
            <?php if (!empty($adminMenuItems) && Flux::config('AdminMenuNewStyle')): ?>
                        <li class="dropdown">
                        <a href="#" class="dropdown-toggle" data-toggle="dropdown">Admin Menu <b class="caret"></b></a>
                        <ul class="dropdown-menu">
                        <?php foreach ($adminMenuItems as $menuItem): ?>
                            <li>
                                <a href="<?php echo $this->url($menuItem['module'], $menuItem['action']) ?>"><?php echo htmlspecialchars(Flux::message($menuItem['name'])) ?></a>
                            </li>
                        <?php endforeach ?>
                        </ul>
                        </li>
            <?php endif ?>

        </ul>
    </div><!--/.nav-collapse -->
</div>