Applying discount to entire category?

I must be doing something wrong. I've created a discount and chose a category, but the discount is not applying. I added a single product and the discount applied. It won't let me add multiple products to a single discount.

This particular category has about 200 products, so I'd like the discount to apply to the entire parent category.

Update: I tried to apply to the parent category and checked "include sub categories" as yes, but it does not apply to the sub categories. But If I create a discount for a single sub category it works.

Here are two screens...the discount of the sub category that worked, the discount of the entire parent category that did not work.

That made no difference.