How to used theme_hook_suggestions for layout ?

Hi Iadd more theme_hook_suggestion for layout Boostrap to alter something HTML. Cause I want handler HTML by pane page ID . I used bootstrap_threecol_stacked for override tempalte. This my code

function mytheme_preprocess_bootstrap_threecol_stacked(&$variables){

  $page = page_manager_get_current_page();
  if(isset($page)) {
    $variables['theme_hook_suggestions'][] = 'bootstrap_threecol_stacked_' . str_replace('-', '_', $page['name']);
  }
}

But this can't load template suggestion !

So. How did i fix it ? Thanks