Query custom post type & custom taxonomy not working!

I have a custom post type ‘promotion’ which is linked to a custom taxonomy type of ‘promotions-cat’. I’ve added ‘cat1’ as a category in this taxonomy.

I’m trying to query this post type and query the category, which is not returning any results:

$query = 'post_type=promotion&';
$query .= 'posts_per_page=-1&';
$query .= 'post_status=publish&';
$query .= 'category_name=cat1&';
$query .= 'orderby=date&';
$query .= 'order=DESC';

$news_list = new WP_Query();
$news_list->query($query);

Tried this too but not working ??
$query .= 'cat=$post-cat_ID&';