Post from child category

Hi there everyone!
I’ve a little problem with query that’s showing post from child category.

I have one category called ie MainCat. This category had two child categories. One of those child cat have one child-child category. The structure is below.

MainCat
– Child1
– Child-Child1
– Child2

I create some ajax slidedown menu that showing child categories of MainCat and their posts. But unfortunatly this solution showing all post from all categories in MainCat when i want to view only post from (first) Child cat. Only post from Child1, Child2 etc. exclude post from Child-Child1. Below is code that i’m using now. Please give some hint about this case how to exclude posts from Child-Child categories.
Greetz!

$catQuery = $wpdb->get_results("
		SELECT * FROM $wpdb->terms AS wterms
		INNER JOIN $wpdb->term_taxonomy AS wtaxonomy ON ( wterms.term_id = wtaxonomy.term_id )
		WHERE wtaxonomy.taxonomy = 'category'
		AND wtaxonomy.parent = 3
		AND wtaxonomy.count > 0");

	foreach ($catQuery as $category) { ?>

<li><a href="#"><?php echo $category->name; ?></a>
		<?php if(query_posts('cat='.$category->term_id) > 1) : ?>

<ul>
				<?php
				while (have_posts()) : the_post(); ?>

<li><a>"><?php echo the_title(); ?></a></li>
				<?php
				endwhile;
				?>
			</ul>
		<?php
		endif;
		?>
		</li>
	<?php
	}
	wp_reset_query();