How to return if a part is on a shelf using FindPartOnRay?

I have a layout like so:

Model -Script -Shelves --Shelf1,Shelf2, etc..

The script is:

function countCrates()
	for i,v in pairs(script.Parent.Shelves:GetChildren()) do
		local ray = Ray.new(
                Vector3.new(v.Position),
                Vector3.new(0,5,0)
            )
		local part = workspace:FindPartOnRay(ray)
		print(v.Name.."Has part on it")
		print(part)
	end
	wait(1)
end


countCrates()

This returns random parts, rather than the crate on each shelf. Why will it not work?

function countCrates()
    for i,v in pairs(script.Parent.Shelves:GetChildren()) do
        local ray = Ray.new(
                Vector3.new(v.Position),
                Vector3.new(0,5,0)
            )
        local part = workspace:FindPartOnRay(ray)
	if part then
        print(v.Name.."Has part on it")
        print(part)
return
end
    end
    wait(1)
end


countCrates()