Not showing image behind

Why isn't it layering? When I put one image on top of another on the timeline is blacks out whatever is behind it.
I attached so you can see what I mean. I have an image of a conquistador and I wanted the old map to still be visible behind him. But when I put him on top everything goes black in the background.
Many thanks.
I attached so you can see what I mean. I have an image of a conquistador and I wanted the old map to still be visible behind him. But when I put him on top everything goes black in the background.
Many thanks.