title: Symfony crawler selectButton method can't get form
body: <p>here is my html</p>
  
  <pre><code>&lt;form  name="station" method="post" action="/stations/new" role="form"&gt;
     &lt;div class="form-group"&gt;
       &lt;label class="control-label required" for="station_name"&gt;Name&lt;/label&gt;
       &lt;input type="text" id="station_name" name="station[name]" required="required" maxlength="255" class="form-control" &gt;
     &lt;/div&gt;
     &lt;div class="form-group"&gt;
        &lt;div class="checkbox"&gt;
          &lt;label for="station_active"&gt;
          &lt;input type="checkbox" id="station_active" name="station[active]" value="1" /&gt;Active&lt;/label&gt;
        &lt;/div&gt;
     &lt;/div&gt;
     &lt;div class="form-group"&gt;
       &lt;button type="submit" id="station_submit" name="station[submit]" class="btn btn-primary"&gt;Ajouter&lt;/button&gt;
     &lt;/div&gt;
     &lt;input type="hidden" id="station__token" name="station[_token]" class="form-control" value="aze123aze" &gt;
  &lt;/form&gt;
  </code></pre>
  
  <p>i want to get my form using the crawler. I tried the selectButton method like this </p>
  
  <pre><code>$form = $crawler-&gt;selectButton('station[submit]')-&gt;form(array());
  </code></pre>
  
  <p>but i get the error : <code>InvalidArgumentException: The current node list is empty.</code></p>
  
  <p>what is the problem ?</p>