hooked gallery shortcode attributes returns empty

Hi, I am trying to hook the gallery shortcode of wp but ithe ids returns empty. this is my code:

add_filter( 'post_gallery', 'semantic_gallery2', 10, 2 );

function semantic_gallery2( $attr) {
	$post = get_post();

	static $instance = 0;
	$instance++;

	//
	if ( ! empty( $attr['ids'] ) ) {
		// 'ids' is explicitly ordered, unless you specify otherwise.
		if ( empty( $attr['orderby'] ) )
			$attr['orderby'] = 'post__in';
		$attr['include'] = $attr['ids'];
	}

	if ( isset( $attr['orderby'] ) ) {
		$attr['orderby'] = sanitize_sql_orderby( $attr['orderby'] );
		if ( !$attr['orderby'] )
			unset( $attr['orderby'] );
	}

	extract( shortcode_atts( array(
		'order'      => 'ASC',
		'orderby'    => 'menu_order ID',
		'id'         => $post->ID,
		'itemtag'    => 'dl',
		'icontag'    => 'dt',
		'captiontag' => 'dd',
		'columns'    => 3,
		'size'       => 'large',
		'include'    => $attr['include'],
		'exclude'    => '',
		'link'       => '',
	), $attr, 'gallery' ) );

....

this is the shortcode:

[gallery columns="4" ids="11633,11632"]

in default, the ids is not empty, I was wondering that when I hook it, it became empty… I have already took the same code of the media.php…

please help…