$(...).gantt is not a function
<p>I want to display some gantt-charts on my website, but they won't show up. Instead I get a TypeError.</p>

<p>The Site (not fully shown):</p>

<pre><code>&lt;body&gt;
   {% block body %}
       &lt;div class="container"&gt;
          &lt;div class="gantt" id="gantt"&gt;&lt;/div&gt;
          //... some stuff (only &lt;div&gt;&lt;/div&gt; and some &lt;span&gt;&lt;/span&gt; tags)
          &lt;div class="gantt" id="gantt2"&gt;&lt;/div&gt;
          //... even more stuff
          &lt;div class="gantt" id="gantt3"&gt;&lt;/div&gt;
       &lt;/div&gt;
   {% endblock %}

   //Here I include the jquery.fn.gantt.js, etc.
   {% block javascripts %}
        {% javascripts '@jquery_js' '@bootstrap_js' '@jquery_gantt' combine=true       %}
        &lt;script src="{{ asset_url }}"&gt;&lt;/script&gt;
        &lt;script&gt;
            $("#gantt").gantt({
                source: [{
                    name: "Example",
                    desc: "Lorem ipsum dolor sit amet.",
                    values: [{
                            from: "/Date(1333411200000)/",
                            to: "/Date(1328832000000)/",
                            label: "Example Value",
                            desc: "Something",
                            customClass: "ganttRed"}]
                    }],
               scale: "weeks",
               minScale: "hours",
               navigate: "scroll"
           });
           $("#gantt1").gantt({
               source: [{... same as above ...}],
               scale: "weeks",
               minScale: "hours",
               navigate: "scroll"
           });
           $("#gantt2").gantt({
               source: [{... same as above ...}],
               scale: "weeks",
               minScale: "hours",
               navigate: "scroll"
           });
        &lt;/script&gt;
        {% endjavascripts %}
    {% endblock %}
&lt;/body&gt;
</code></pre>

<p>and the config.yml:</p>

<pre><code>jquery_js:
    inputs:
        - '%kernel.root_dir%/../vendor/components/jquery/jquery.js'
        - '%kernel.root_dir%/../vendor/components/jquery/jquery.min.js'
bootstrap_js:
    inputs:
        - '%kernel.root_dir%/../vendor/components/bootstrap/js/bootstrap.min.js'
jquery_gantt:
    inputs:
        - '%kernel.root_dir%/../src/AppBundle/js/jquery.fn.gantt.js'
        - '%kernel.root_dir%/../src/AppBundle/js/jquery.fn.gantt.min.js'
</code></pre>

<p>If I run this code now, nothing happens except that this error appears:</p>

<pre><code>TypeError: $(...).gantt is not a function
</code></pre>

<p>I don't know what's happening or how to fix this, as everything seems correct to me. the .js/.css-files are included and load correctly.</p>