Sub-sub categories have no random thumbnail

Hi, I wanted to create a sub-subcategory which is 3 levels deep as shown in the screen capture below, and show a random thumbnail image from the subcategory, but it's not showing me any random image:

Here's my category structure...

In Gallery View/Random Thumbnail, I have it set to "from both", and in the actual gallery, it shows this:

How do I get it to show a random thumbnail for the subcategories of "Disney Characters"?

Should there be a "from all" Random Thumbnail option?

Thanks,
Dan

Follow-up, never mind, I figured this out. In "Category View", there is a tab for "Sub-Categories". Under "Random Thumbnail", I just selected "from both" and it worked fine.