Fatal error: Call to undefined method stdClass::get_variables()

Hi all!

Need some help, becouse i'm realy stuck on getting comments from content_profile on my users profile pages.
What i do:

In user-profile.tpl.php:

  $node = NULL;
  $node_profile = $content_profile->get_variables('profile');
  if($node_profile)
    $node = &$node_profile['node'];
  // [ ... ]
  // This is the ready-for-print variable for the user profile data
  print $user_profile;
  // [ ... ]
  // Print this wherever you want to show the node_profile content
  print node_view($node, FALSE/*teaser*/, TRUE, TRUE);
  // [ ... ]
  // Put this where you want to show your comment block
  if ($node && function_exists('comment_render')){
    if( $node->comment)
    {
      print comment_render($node);
    }
  }

and that code causes an error:
Fatal error: Call to undefined method stdClass::get_variables() in user-profile.tpl.php on line 132

What i'm doing wrong?