display fixed size thumurl

i have used this code in my index.php page:

<?php $thumurl = wp_get_attachment_url( get_post_thumbnail_id($post->ID),’large’ );?>
<img src=”<?php echo $thumurl;?>” height=”200″ width=”200″ alt=”” />

and this in the function.php:
add_theme_support(‘post-thumbnails’);
set_post_thumbnail_size( ‘200’, ‘200’ );

i want to display the multi size uploaded thumurl into the same size.
why is these code not working?