title: hook_form_alter changes array, but is not rendering in contact form
body: <p>I use hook_form_contact_site_form_alter to alter the Conact Form. Everyting works fine when I change the array, for example:</p>
  <pre><code>  $form['firstname'] = array (
      '#type' =&gt; 'textfield',
      '#title' =&gt; t('FirstName'),
      '#maxlength' =&gt; 255,
      '#required' =&gt; true
  
    );
  </code></pre>
  <p>dpm($form); shows me this:</p>
  <p><img src="https://i.stack.imgur.com/LSVjh.jpg" alt="enter image description here" /></p>
  <p>So, thats perfect</p>
  <p>... but nothing renders! Its still the good old default contact form:
  <img src="https://i.stack.imgur.com/VNsxu.jpg" alt="enter image description here" /></p>
  <p>I was thinking, that maybe another hook overrides mine, or that I have to tell Drupal to rebuild the form. I haven't found anything usefuls in the API Reference yet.</p>
  <p>Maybe somebody else had the same problem, or knows a good method to debug?</p>
  <p>Thanks in Advance</p>
  <p>btw. I had the contact_forms module installed, but uninstalled it again, maybe this is related.</p>