contents does not save in custom sidebar widget

Hi all,
I am using WP 3.4.1
I created a custom sidebar widget for showing related posts.
my code is

if ( function_exists('register_sidebar') )
    register_sidebar( array(
   'name' => __('Related Posts Widget Area'),
   'id' => 'relatedpostsWidgetArea',
   'description' => __( 'A widget area for displaying realted posts on side bar', 'academica' ),
   'before_widget' => '<aside id="%1$s" class="widget %2$s">',
   'after_widget' => "</aside>",
   'before_title' => '<h3 class="widget-title">',
   'after_title' => '</h3>',
   ) );

it appears in admin menu,but when i save any contents in it,the content disappear and gone.it dose not save.
any help/idea appreciated.