title: embed block anywhere fails at drupal 7
body: <p>It's been a week I have played around with drupal 7. With drupal 6, I used to be able to place (login) block anywhere with this:</p>
  
  <pre><code>  $block = (object) module_invoke($module, 'block', 'view', $delta);
    $block-&gt;module = $module;
    $block-&gt;delta = $delta;
    return theme('block', $block);
  </code></pre>
  
  <p>or this:</p>
  
  <pre><code>$block = module_invoke('user', 'block', 'view', 0); 
  $vars['login'] = $block['content'];
  </code></pre>
  
  <p>I changed the delta '0' for Drupal 7:</p>
  
  <pre><code>$block = module_invoke('user', 'block', 'view', 'login'); // I have changed from 0 to 'login' for delta at drupal 7
  $vars['login'] = $block['content'];
  </code></pre>
  
  <p>Both result in Fatal error. Any change that I am not aware of with module_invoke? There is no specific change at <a href="http://api.drupal.org/api/drupal/includes--module.inc/function/module_invoke/7" rel="nofollow">http://api.drupal.org/api/drupal/includes--module.inc/function/module_invoke/7</a></p>
  
  <p>Any hint would be very much appreciated.</p>