CCNA, CCNP, MCSA, CCNA Final Exam, All Answer Test Module With 100/100

When publishing content or changing any settings in the admin, the screen goes blank, I found that it's due to this code in my functions.php file. Is there something wrong with it? <?php if ( function_exists('register_sidebar') ) { register_sidebar(array( 'name'=> 'Footer', 'id' => 'footer', 'before_widget' => '', 'after_widget' => '', 'before_title' => '<div class="title">', 'after_title' => '</div>' )); register_sidebar(array( 'name'=> 'Right-Sidebar', 'id' => 'rightsidebar', 'before_widget' => '<div class="white-bar">', 'after_widget' => '</div>', 'before_title' => '<div class="title">', 'after_title' => '</div>' )); register_sid...