MVC Dropdown in bootstrap not working?

[M1kkelZU]

I'm trying to make a dropdown menu appear on click in a menu. My current code looks like this:

<div class="container-fluid">
        <div class="row">
            <div class="col-sm-3 col-md-2 sidebar">
                <ul class="nav nav-sidebar">
                    <li><a href="">Home</a></li>
                    <li><a class="dropdown-toggle" href="#">Opleiding<span class="caret"></span></a>
                            <ul class="dropdown-menu">
                                    <li><a href="#">TEST</a></li>
                            </ul>
                    </li>
                    <li><a href="#">Locaties</a></li>
                    <li><a href="#">Docenten</a></li>
                    <li><a href="#">FAQ</a></li>
                    <li><a href="#">Contact</a></li>
                </ul>
            </div>

I've tried using:

<li><a class="dropdown-toggle" data-toggle="dropdown" href="#">Opleiding<span class="caret"></span></a>

but to no avail, my data-toggle doesnt recognize "dropdown" but only "collapse". Is what I want to do possible or am I just goofing up?

Thanks!