Frustrated! Can't embed regions, blocks, views, anything in user_profile.tpl.php

Hey all

I have an extremely frustrating problem with embedding pretty much anything in my custom user profiles. Maybe there's something not apparent here, maybe you can see it.

In my template.php I have this callback. I'm told this is standard fare for profile customization.

function phptemplate_user_profile($user, $fields = array()) {
  // Pass to phptemplate, including translating the parameters to an associative array. The element names are the names that the variables
  // will be assigned within your template.
  /* potential need for other code to extract field info */
return _phptemplate_callback('user_profile', array('account' => $user, 'fields' => $fields));
  }

My templating is done via path:

function _phptemplate_variables($hook, $vars = array()) {
  switch ($hook) {
   
    case 'page':
	if (drupal_is_front_page()) {
      $suggestions[] = 'page-index';
    }
      if (module_exists('path')) {
        $alias = drupal_get_path_alias($_GET['q']);
        if ($alias != $_GET['q']) {
          $suggestions = array();
          $template_filename = 'page';
          foreach (explode('/', $alias) as $path_part) {
            $template_filename = $template_filename . '-' . $path_part;
            $suggestions[] = $template_filename;
          }
        }
        $vars['template_files'] = $suggestions;
      }  global $user;
      
      break;

I have two templates, a page-user.tpl.php and a user_profile.tpl.php.

In page-user.tpl.php, all I have is

<? print $content ?>

In my user_profile.tpl.php I have all my customizations for my profile, such as markup, scripts, dumping field content etc, which works fine.

Now, in user_profile.tpl.php, if I try to embed a block with module_invoke, or try print out a region which I know contains a block or content, such as <? print $header ?> , I get nothing whatsoever. No markup, no content, nothing.

However, if I backtrack, go to page-user.tpl.php and place <? print $header ?>, voila, it works. Why can't user_profile.tpl.php see blocks, views, etc? but page-user.tpl.php can??