get_children in archive

Hi,
I have problems to get some images with this code inserted in a post inside the category page:

$args = array(
	'numberposts' => 1,
	'order'=> 'ASC',
	'post_mime_type' => 'image',
	'post_parent' => $pageChild->ID,
	'post_status' => null,
	'post_type' => 'attachment'
	);
	$attachments = get_children( $args );
	if ($attachments) {
		foreach($attachments as $attachment) {
			$myimg= '<img src="'.wp_get_attachment_thumb_url( $attachment->ID ).'>';
		}
	}

I read a lot of posts in this forum but nobody gave the right answer… please help me!!