problem with get_parent_category()

I have got

cat top ( 2 post )
sub cat1 ( 3post )
sub cat2 ( 4post )

when i click on cat top catecory it show only posts of sub cat1 and sub cat2 ( 3+4 posts )
but where is 2 posts of cat top
I am using this code

foreach((get_the_category()) as $category) {
	$Cat_ID = $category->cat_ID;
}

it returns
cat top ( id of sub cat1 )
sub cat1 ( id of sub cat1 )
sub cat2 ( id of sub cat2 )

who can help me ?