Help with the Gallery plugin - Path to resources inside a folder

Things I have tried

I have tried path=books/covers
The folder is books and the page with the images is covers

I can do path:/
But this shows the entire vaults images.

type=active-thumb
path=books/covers
imgWidth=400
divWidth=100

Sorry if this is a dumb question but I have been trying everything I could think of.

Otherwise when I try to specify a path, literally any path. It shows up blank