WP_Query: Trouble with arguments "cat" and "category_name"

Hi there,

Thanks for stopping by.

I’m having trouble displaying posts in specific categories.

My query looks like this:

<?php $loop = new WP_Query(
array( 'cat' => '42',
'posts_per_page' => '5',
'order' => 'DESC'
); ?>

I’ve created a category called “Featured” (slug: “featured”:wink:, for featured posts on the home page.

I can get any other posts to display, as long as I’m not choosing specific categories.

I’ve always had trouble with the arguments “cat” and “category_name”, as well as “category__in”. What am I doing wrong here?