WP_Query with Custom Taxonomy

I’m trying to use WP_Query to get all of a custom post type which contains a specific custom taxonomy.

I’ve tried the new and old styles and I can’t give it to give me what I want. It seems to basically be ignoring it completely, only using the post_type.

I’ve tried:

array('post_type' => 'my_type', 'tax_query' => array(
				'taxonomy' => 'my_taxon',
				'field' => 'slug',
				'terms' => 'my_slug',
				'operator' => 'IN');

array('my_taxon' => 'my_slug', 'post_type' => 'my_type')

and a few more. It just gives me all of the posts in that post type, not limiting them by the taxonomy.

Any ideas?