$items['custom_report/glp_report'] = array(
'title' => 'GLP Report',
'description' => 'Report for Guided Learning Pathways.',
'page callback' => 'op_reports_page',
'access callback' => 'op_reports_permission',
 //'theme callback' => 'op_theme',
'type' => MENU_NORMAL_ITEM,
);

$items['admin/custom_report/glp_report'] = array(
'title' => 'GLP Report',
'description' => 'Report for Guided Learning Pathways.',
'page callback' => 'op_reports_page',
'access callback' => 'op_reports_permission',
 //'theme callback' => 'op_theme',
'type' => MENU_NORMAL_ITEM,
);

<!-- BEGIN OUTPUT from 'sites/all/themes/bootstrap/templates/block/block.tpl.php' -->

<!-- BEGIN OUTPUT from 'modules/block/block.tpl.php' -->

function op_reports_page() {
$page = drupal_render(drupal_get_form('op_reports_form', 'glp'));
$page .= op_reports_table('glp');

$page = array
(
'op_reports_page' => array
(
// Note - we will register theme_my_page in the next step
'#theme' => 'glp_reports',
'#contents' => $page,
),
);

return $page;
}

function op_reports_theme()
{
  return array
  (
    'glp_reports' => array
    (
      'variables' => array('contents' => array()),
      'template' => 'op_theme', // don't add .tpl.php
    ),
  );
}

<h2><?php print t('My Page'); ?></h2>
<div id="my_page_wrapper">
  <?php print render($contents); ?>
</div>

$items['admin/custom_report/glp_report'] = array(
    'title' => 'GLP Report',
    'description' => 'Report for Guided Learning Pathways.',
    'page callback' => 'op_reports_page',
    'access callback' => 'op_reports_permission',
    'theme callback' => 'op_theme', //name of bootstrap extended theme
    'type' => MENU_NORMAL_ITEM,
  );

function op_reports_custom_theme(){
    return 'op_theme';
  }